The term "agent name delivery" is the process that displays web content to users depending on their user agent. This function can be used positively for better page display in certain browsers and negatively for webspam.
If a web server is accessed, the agent name delivery function is used to determine which user agent is accessing it. The system distinguishes between a human user who uses a browser or a bot. Once the type of agent has been detected, the server can output adapted content. Browser switches, which can recognize the agent, are used for this purpose.
Web browsers can be different in their presentation of web content. To ensure the optimum screen view for all users, the agent name delivery function can be used to output content using a browser switch so that it is optimally displayed for each browser.
HTML content can be adapted to Mozilla’s Firefox or Google Chrome. Moreover, the agent name delivery function can also detect whether a user is accessing web content from a mobile device or a desktop PC. It can even determine the specific smartphone type. In this case, the agent name delivery function plays a role in mobile optimization responsive design.
Agent name delivery is often associated with spam techniques. In this case, the search engine bot is shown a different page version than the one displayed to a “real” visitor. The page version which is output to the bot almost exclusively contains text elements with an accumulation of keywords, while the human visitor sees an ordinary website. This technique is considered cloaking and a violation of the Webmaster Guidelines for search engines, and thus may result in exclusion of the website from the index of a search engine. In many cases, search engine robots are disguised as a web browser in order to crawl the actual visible version of a website. In fact, there is a lot of speculation if the Googlebot is disguised as a Mozilla bot.
However, if agent name delivery is supposed to be used only to adapt the website content via browser switches for different browser systems or devices, it is part of an SEO strategy that should be used to improve usability further, but due to the “disguise possibility” of many user agents it does not always work reliably.