Understanding how your ads affect your website traffic is crucial to a successful campaign. Correct use of the auto-tagging feature in Google Analytics (or other web analytics software) and Google Ads or Floodlight in Google Display & Video 360 can help you track the performance of your campaigns and identify the portion of your website visits that correspond to paid clicks.

Web server logs are where your web server keeps an anonymous history of the activities it performs. Usually, this includes:

• The IP address that issued the request
• The date and time of the request
• The resource (i.e., web page, image, etc.) that was requested
• The user agent (i.e., detailed information about the operating system and browser) that issued the request
• The success of the request
• The referrer of the request

Please note the information your web server records will depend on the configuration of the server. If your logs don't contain all of the aforementioned information, your web server might be set to record its activities according to the common log format.

If that's the case, change your web server's configuration to track its activities according to the combined log format. (Note: some log formats may have different names depending on who built your web server.)

Below is a snippet of an Apache web server log in the combined log format:

172.26.136.223 - - [19/Jul/2011:15:25:57 +0100] "GET /index.html HTTP/1.1" 200 11579 "http://www.google.com/search?q=movies+shop" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"
172.26.136.223 - - [19/Jul/2011:15:26:30 +0100] "GET /books.html HTTP/1.1" 200 21176 "http://www.example.com/index.html" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"
172.26.136.223 - - [19/Jul/2011:15:27:21 +0100] "GET /movies.html HTTP/1.1" 200 26781 "http://www.example.com/contact.html" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"
172.26.136.223 - - [19/Jul/2011:15:27:55 +0100] "GET /movies.html?id=12341 HTTP/1.1" 200 8404 "www.example.com/movies.html" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"
172.26.136.223 - - [19/Jul/2011:15:27:55 +0100] "GET /movie.jpg HTTP/1.1" 200 320362 "http://www.example.com/movies.html?id=12341" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"

A complete log often includes millions of entries and can grow by hundreds or thousands of new entries or more each day.

It's worth noting that a single entry doesn't necessarily represent a unique user or a single page impression. One page request can, and mostly will, trigger a large array of requests for images, CSS files and the like that are saved in the web server log.

In the above snippet, this can be seen in the last two entries. The second entry from the bottom is for the HTML file of the page. The last entry is for a picture - in this case, movie.jpg - that is embedded in the requested page (movie.html?id=12341).

The following paragraphs explain in more detail the information that is decoded in a single entry:

172.26.136.223 - - [19/Jul/2011:15:27:55 +0100] "GET /movies.html?id=12341 HTTP/1.1" 200 8404 www.example.com/movies.html" Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"

The red number "172.26.136.223" states the IP address of the computer that requested the page. Sometimes, a unique IP address indicates a unique user. However, most mobile carriers and some Internet Service Providers (ISP), rotate IP addresses among their users. In these instances, the IP address assigned to a particular user when they connected to the Internet could have been assigned to another user who disconnected just moments earlier.

In addition, organisations like companies and universities usually use proxy servers to handle all of their Internet traffic. This means that, for instance, all of the students of a university would appear to share the same IP address in your web server logs, even though they are in fact many different unique users.

The yellow string "[19/Jul/2011:15:27:55 +0100]" refers to the date and time of the request, while the blue string "/movies.html?id=12341" denotes the page that was requested.

The green string "www.example.com/movies.html" states the referrer of the request. Usually it denotes the web page that the user loaded before it was loaded on your web server.

Please note that without URL tracking, referrers generated from clicks on normal search results and ads will look the same. In some cases, there may be no referrer information at all. This can happen for a variety of reasons: maybe the user accessed the website directly by typing the URL, the user's browser doesn't support URL tracking, or the user deactivated the feature.

The long purple string "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30" shows the visitor's user-agent, including the operating system and browser version the visitor is using to access the website. However, this information is very easy to fake, so do not rely too heavily on this data.

Don't want to read hundreds of thousands of raw web server logs a day? Fortunately, there's software to do it for you. For example, Google Analytics, uses JavaScript to gather information about the users of a website, then present the data in a much more readable format.

If you want to use third party tracking software, choose carefully. In general, the most accurate third party programs for tracking clicks are those that require auto-tagging to be enabled in Google Ads and Third Party Tags in Google Display & Video 360. Please keep in mind that charges are based solely on Google's metrics.

URL tracking distinguishes between clicks that come from Google Ads or Google Display & Video 360 and those that are from other sources, like Google search results. In the absence of tracking URLs, the log of requests generated by a user that clicked on an ad, and clicked an organic search result on google.com, might look like the following:

172.26.136.223  - - [19/Jul/2011:15:27:55 +0100] "GET /movies.html HTTP/1.1" 200 8404 "www.google.com" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30" 172.26.136.223 - - [19/Jul/2011:19:21:43 +0100] "GET /movies.html HTTP/1.1" 200 8404 "www.google.com" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"

As you can see in this example, there is no way to distinguish between clicks from Google Search and an ad.

URL tracking works by assigning unique Destination URLs to the landing pages used in a site's campaigns. For instance, in addition to the usual index.html page, there would also be a copy with the same content called index_GoogleAds.html.

In the above example, any campaigns that drive traffic to the index page would use index_GoogleAds.html URL as their Destination URL. Then, the corresponding log entries would look something like this:

172.26.136.223  - - [19/Jul/2011:15:27:55 +0100] "GET /movies_GoogleAds.html HTTP/1.1" 200 8404 "www.google.com" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30" 172.26.136.223 - - [19/Jul/2011:19:21:43 +0100] "GET /movies.html HTTP/1.1" 200 8404 "www.google.com" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"

Basic URL tracking is very easy to implement. For even greater granularity, you can associate a unique landing page with each of the keywords in your campaign.

However, URL tracking is not 100% accurate, since the requests don't necessarily correspond to ad clicks. For example, a user might click on an ad and then bookmark the landing page, or go past the landing page and return to the page by hitting the "back" button on their browser. For a more accurate tracking method, try auto-tagging.

Auto-tagging is a feature in Google Analytics and Google Ads or Google Marketing Platform that automatically appends a unique parameter to each click received by an ad. This parameter is called the "GCLID" and each click has a unique one. A log entry for a campaign using auto-tagging would look like this:

172.26.136.223 - - [19/Jul/2011:19:21:43 +0100] "GET /movies.html?gclid=CLzkq4Lcz5ECFQcKGgodwjgiyA HTTP/1.1" 200 8404 "www.google.com" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.122 Safari/534.30"

The red string is the GCLID parameter. If you have auto-tagging on and configured correctly, only the log entries with a GCLID parameter are clicks from Google Ads or Display & Video 360. Even if you find several entries with the same GCLID, you will only be charged for at most one click.

Using auto-tagging and Google Analytics allows you to see which keyword brought a visitor to your website, where that visitor is from, which campaign the keyword was associated with, and how much the click cost.

You can easily calculate your return on investment (ROI) for a given campaign by associating this data with goals or e-commerce conversions. Based on that data, you can then decide how to optimise your advertising campaign.

Some advertisers struggle to understand their web log data, especially when they haven't enabled auto-tagging or are using third-party tracking software that lacks support for auto-tagging.

The most common misunderstandings are related to:

• Discrepancies between clicks and visits

  Misunderstanding the relationship between clicks and visits can make it seem like there's a discrepancy between the information in your web server logs and the information provided by Google Ads or Display & Video 360.

  In general, Google Ads and Display & Video 360 track clicks, while many tracking services count visits. When someone sees your ad, clicks the title, and lands on your website, that's a click. Visits, particularly unique visits, are the number of unique sessions initiated by visitors. Because clicks and visits measure slightly different things, there are several reasons why the number of clicks and visits may not match.

• Short visit times and high bounce rate

  Many advertisers worry about very short visit times (i.e. zero-second visits) or high bounce rates (watch this video explaining bounce rate). Neither one necessarily means that a user left your site the instant they loaded it. All it really means is that they left the site from the landing page without viewing any other pages. If this happens a lot, it can mean that your site is hard to navigate or that you've implemented your tracking code incorrectly, so take a critical look at your site if you see either of these in your site statistics.

• Relationship between IP address and people

  Many people believe that IP addresses are unique to individual people, like fingerprints. But that's not always the case. There are several reasons why web log entries with the same IP address might belong to several different users. For example, some ISPs assign IP addresses dynamically, cycling through the same limited number of IP addresses with several users as they connect to the Internet one after another.

The bottom line is that enabling auto-tagging is a simple and highly effective way to improve how you track your campaign activity, because it provides insight into every click and helps navigate the pitfalls associated with identifying users solely by IP address.

Adding a CAPTCHA to your forms will help validate that the person submitting it is human. Not all CAPTCHAs are created equal, so if you already use one but are still getting fake leads, try another one. We recommend the free captcha service offered by Google.

If you use Google Ads to generate traffic to your landing pages, we recommend you enable auto-tagging. Auto-tagging will attach a GCLID-parameter to the URL of each landing page that identifies the pageview as the result of a click on your ad.

If you have auto-tagging enabled but you don't see this parameter in your site activity, it's safe to say that those visits didn't come from your ad.

When a visitor submits information on your website, you may want to record the IP address, the GCLID-parameter (if applicable), the referrer URL and user agent. You can use these details to see where your traffic is coming from and look out for any suspicious patterns. (Please note that you may need to talk to your webmaster or IT department to implement these types of changes.)

If you do see a suspicious pattern from visitors arriving through your Google Ads or Display & Video 360 campaigns, please contact your relevant product representative using our invalid clicks troubleshooter and forward the GCLIDs or IP addresses to Google. Our Ad Traffic Quality team will then investigate your account.

You may occasionally notice an increase in the number of clicks your ads receive. This might raise concerns about potentially invalid clicks, but in most cases these fluctuations are caused by other factors.

By performing simple checks on your account, you can often identify the reason for increased clicks. In many cases, understanding the reason for the increase can help you to identify opportunities for campaign optimization.

Changes in the account

Campaign changes can have a significant impact on the performance of a campaign. The most common ones to keep in mind are:

• Changes to daily budget

  Increasing the daily budget for your campaigns will allow the ads to receive more impressions and, naturally, more clicks.

• Changed to maximum CPC for keywords

  Increasing the maximum CPC for one or more keywords may cause your ads to appear more often, or in a higher position than before. Ads in a higher position typically receive more clicks than those in a lower position. This is also true for ads that show in Google Display Ads - a higher CPC can push ads into a higher position, which means more impressions and more clicks.

• New keywords

  Adding new keywords to your campaign, especially if the keywords are quite general or correspond to popular search queries, can increase the number of impressions and clicks.

• Changes to country or language targeting

  Adding new countries or languages to a campaign's targets can significantly increase the number of impressions and clicks.

• Changes to the network settings

  Targeting new placements, or switching from automatic to managed placements (or vice versa), can also influence your campaign's traffic.

In general, if you optimize a campaign to improve its performance, it may result in a higher quality score for your keywords, which will give them a higher position for a lower CPC. As a result, you may get more impressions and clicks for the same daily budget.

External factors

Sometimes you may notice fluctuations in traffic, even though you haven't made any changes to a campaign. Here are a few of the most common reasons:

• Ads are showing on new Display Network sites

  If your campaign uses automatic placements and has enough daily budget, an ad's traffic can significantly increase if it starts showing on a new publisher site, or if the sites suddenly receive more traffic due to:

• Seasonal trends or news events

  A sudden spike in interest in a specific topic can cause increased traffic, such as a celebrity endorsement of a specific product, a related news event, or special occasions like Valentine's Day.

• Changes in the competitive landscape

  If one of your competitors stops advertising or changes their campaigns, your ads may see an increase in impressions and clicks due to reduced competition.

Review your account for campaign changes that might explain the increase

• Compare the campaign graphs for clicks and impressions over a longer period of time to pinpoint the change. Comparing the impression graph to the average position graph can show you whether the traffic increase was the result of a change in the ads' average position.
• Check the change history for budget, CPC, or other changes that could have caused the increase.
• Check the search terms that triggered the ads for any top search terms that may have caused the traffic.
• Check the invalid clicks report to see if there was an increase in invalid click activity that was automatically filtered from your reports.

Check for external factors that might have influenced the campaigns performance

• Use Google Trends to look at the search trends for the top terms that triggered your ads. Google Trends may also show related news stories, which may explain the increase in interest.
• Think of any news events, holidays, or seasonal trends that could have caused a spike in interest.

As you review your account you may find some opportunities to make further campaign changes. For example, if you see that your ads received more clicks because of an increased number of searches for a seasonal term (for example, "ceiling fans" during a hot summer), you may want to change CPCs and budget to take advantage of the increased interest.

However, if your ads for ceiling fans are showing for search terms like "excited fans storm concert hall," your campaign could benefit from some keyword optimization. Try adding negative keywords or choose more restrictive keyword matching options. You can find a more detailed list of optimization tips in our Help Center.

Focus on your ads' return on investment (ROI) instead of the number of clicks. An increase in impressions and clicks, if combined with an increased number of conversions (for example, sales or leads), is actually a good thing.

We recommend the use of conversion tracking and Analytics to better understand what you're getting for the money you spend on advertising. Our help center has detailed information about how to improve the ROI of Google Ads campaigns.

If you suspect that your account is being affected by invalid clicks, impressions, or other traffic, our team of specialists can investigate for you. However, many suspected cases of invalid traffic are actually the result of valid reasons for increases. For example, your ads may be showing more often on the network, or you may have recently increased your daily budget.

A lot of the time, a quick account check can help you identify the reason for the traffic fluctuation and make campaign adjustments to improve your ROI.

Our Ad Traffic Quality team uses a variety of different signals, including click and impression information, to identify sources of invalid activity. Because we look at such a large number of data points, it may take several days to complete the investigation into your account.

When requesting an investigation, please share as much information as you have about the traffic in question. At a minimum, please provide the following details:

• Customer ID. If you're an agency, provide the specific customer ID of the account where you suspect invalid activity and not your agency customer ID.
• Your contact email address. Verify that the email address is valid and can receive email from google.com.
• Date range of the activity. Please note that Google disclaims all liability for traffic accrued 60 days prior to the date of requesting an investigation.
• Campaign Name, ad group name, and/or the keyword affected by the activity.
• Domain name of the publisher site, if you suspect you've received invalid activity from a specific site in the Google Search or Display network.
• A short summary of why you believe the click activity is suspicious. This helps us learn more about the activity and enables us to address your specific concern.

The above information is usually sufficient to investigate a case, but any additional information about the traffic and suspicious patterns will be very useful. This may include:

• IP addresses. This is especially helpful if you suspect a limited number of IP addresses are causing the activity. You can also submit the IP subnets.
• GCLID values.
• User agent and referrer URL information.

You can find most of these details in your web logs. When you submit the form, just attach a document specifying the suspicious patterns and/or traffic that you've noticed.

To contact our support team, please follow the step-by-step guide in our Help Center.