• Anchor Text - The text visible when looking at a hyperlink. For example:

  <a href='somepage.html'>Click Me</a>

  In this example, "Click Me" is the anchor text. Anchor text is important for search engines to determine what your page is about.
  
• Back Link - A link back to your site from an external website. The more backlinks you have, the better.
  
• Bot (aka Spider) - A computer program that searches through and indexed web pages on the internet. When striving for search engine optimization, you are working to make it easier for bots to "crawl" your site.
  
• Cloaking - Practice whereby your webpage changes or contains different/additional content when viewed by a bot as opposed to being viewed by a human. This practice, if discovered, can cause you to be banned from search engine listings.
  
• Doorway Page - Several other terms refer to the same thing (i.e. gateway page). This is a practice whereby you have a page setup that spiders index which ranks well, however the page is just a doorway to other unrelated content. Like cloaking, use of a doorway page can often result in your site being banned from search engine listings.
  
• Gateway Page - See doorway page
  
• Keyword / Keyphrase - Term used to describe the words typed into a search engine query box. Search Engine Optimization primarily centers around working to ensure your site ranks high for keywords and keyphrases related to your site's content.
  
• Keyword Stuffing - Practice of adding keywords to a page (often in sneaky ways) in an attempt to trick search engine bots into ranking your site higher for those words. For example, some webmasters will put several keywords in a hidden div (html content that is not actually displayed in a browser but can be viewed in the source code), use a font color that is the same color as the background color so it is unreadable by humans, or put several terms at the very end of a page below the main content. Depending upon the implementation, this may or may not be a violation of the Terms of Service of most search engines (for example, if the text is not visible to humans) and there is no reason to engage in this activity.
  
• Link Farm - Webpage soley for the purpose of linking to several other webpages in an attempt to increase the number of back links and raise a site's search engine rank. Search engines generally frown upon link farms and do not give much weight to the site's linked to from a link farm.
  
• PR / Page Rank - Google's unofficial measure of the importance of a web page. A high page rank is something most webmasters strive to acheive, however a high page rank does not necessarily mean your site will rank high for specific keyword searches.
  
• robots.txt - A file that can be uploaded to directories on your webserver which bots can read. The file instructs bots which links and folders that may or may not follow. You can read more at the Web Robots Pages.
  
• SEO / Search Engine Optimization - Practice of optimizing your site so that search engine spiders can crawl it easier, and so that your site ranks better for the market or subject it caters to. There are many practices involved with Search Engine Optimization, including (but not limited to) using friendly urls, using appropriate html tags, building up relevant and related back links to your site, and using tools provided by search engines to understand how they see your site.
  
• SERP / Search Engine Results Page - The results page generated when you type in keywords to a search engine query form. Part of SEO is attempting to ensure your site is listed higher on SERPs.
  
• Spam - The term spam is rather generic these days. It used to refer specifically to unsolicited email, however as the internet has evolved people have figured out other ways to spam. For example, many blogs and guestbooks allow visitors to leave comments - untoward users can leave spam comments purely for the purpose of linking back to their site, in an attempt to gain more backlinks and higher positioning for the keywords they use in those backlinks. Spam is a direct violation of most search engine Terms of Service, and further to that is annoying, unwarranted, and unsightly.
  
• Spider - (See bot)
  
• Spider Trap - Practice of identifying and "trapping" spiders - either by forcing them to a specific page of a site, or not allowing them to view requested pages.
  
• Stop Words - Words ignored by search engines because of their overly common usage. For example: and, the, am

These are some of the more common general terms when referring to Search Engine Optimization. There are dozens of other terms that are commonly used when referring to search engine optimization, website maintenance, and so on. If you didn't find what you were looking for, then you may want to try one or more of the following comprehensive glossary listings:

• Search Engine Dictionary
  
• SEOGlossary.com
  
• Search Engine Marketing glossary at seobook.com