Contextual advertising scans the text of a website for keywords and returns ads to the webpage based on those keywords. The ads may be displayed on the webpage or as a pop-up ads. It is a form of targeted advertising in which the content of an ad is in direct correlation to the content of the webpage the user is viewing.
Search engine advertising is also a form or contextual advertising, since the ads that appear in the results are based on the keywords in an auction system run by a contextual advertising company. Publisher and advertisers only profit from the ads when a user clicks on the ad, this also known as Paid Per Click (PPC) advertising.
Google AdSense is a contextual advertising program. This program was one of the first of its kind. The process that matches ads to relevant sites in the display network using your keywords or topics, among other factors. Google ‘s System analyzes the content of each page to determine its central theme, which is then matched to your ad using your keywords and topic selections, your language and location targeting, a visitor’s recent browsing history and other factors. Also, adwords uses contextual targeting when an ad group has keywords or topics and its campaign is set to show ads on the Display Network.
It is one of a few different methods that you can use to get your ads on sites and pages that are part of Google’s Display network. This method uses the keywords or topics you’ve chosen to match your ads to relevant sites.
Contextual targeting starts with you adding keywords or topics to ad groups in your Display Network campaigns. Google will analyze the content of each Display Network webpage or URL considering factors such as the language, link & page structure and text. Sometimes your ad may show on placement that seem unrelated to the keywords you are targeting, that is possible that your ads are being shown to someone based on their recent browsing history or other factors, rather than the content of the page they are currently viewing.
There are 2 types of keywords contextual matching:
Keyword Contextual Match: The placement where your ad appears is contextually relevant to your keywords.
Extended Keyword Match: The placement where your ad appears is relevant to your keywords and other factors, including pages a person saw your ad on a page recently browsed.
Googlebot was designed to be distributed on serveral machines to improve performance and scale as the web grows. Also to cut down on bandwidth usage, Google run many crawlers on machines located near the sites they’re indexing in the network.