Bad neighborhoods: Web spammers, link farms, or any other sites or schemes that exist to try to circumvent a search engine’s ranking rules and artificially boost a site’s ranking. Most engines penalize or ban sites that link to bad neighborhoods.

Click fraud: a form of theft perpetrated against advertisers who are paying per click for traffic, in which fraudsters may use automated means to click on your ads from spoofed IP addresses over random periods of time.

Content cloaking: A sort of bait-and-switch tactic in which Web pages are designed with codes, keywords, and other verbiage that are hidden to general users and visible only to search engines; in other words, the site visitor sees one page, and the search engine spider views something else. Most engines penalize or ban sites that practice content cloaking.

Cost per click: Paying for sponsored links or paid inclusion links according to each time a user clicks on a link.

Crawler: Software used by a search engine to find and index pages; also called a robot or a spider.

Deep submitting: Submitting all of your Website’s URLs — in other words, every single page of your site — to a search engine. Most engines forbid this practice.

Doorway page: A Web page with content that’s meaningful or visible only to the search engines; also called a bridge page or a gateway page.

Inbound links: Links leading to a particular Web page; also called backlinks.

Keyword density: The proportion of relevant words and phrases on a Web page; used by search engines as a criterion for determining a listing’s ranking.

Keyword stuffing: Placing excessive keywords into page copy and coding such as meta tags that may hurt the usability of a page but is meant to boost the page’s search engine ranking. Hiding keywords on a page by making them the same color as the page background and loading tags with repeated keyword phrases are examples. Most engines penalize or ban sites that practice keyword stuffing.

Link farm: A page that is simply a collection of other, often unrelated links. Such pages exist solely to try to boost a site’s engine ranking: Google and some other engines calculate a site’s popularity in part by the number of other sites that link to and from it, with more-popular sites often ranking higher than less-popular ones. But the engines also take into account the quality of the linked sites, not just the number of sites that are linked. Therefore linking to link farms is ineffective at best; at worst an engine will penalize or ban a site for doing so.

Link popularity: A measure of the quantity and the quality of inbound links to a Web page; often used by search engines as a criterion for determining a listing’s ranking.

Meta tags: Information placed in a Web page that’s meant to be read only by browser software, search engines, or other applications; includes meta description tags (in which page authors can indicate to search engines how they want the page described in its listing) and meta keyword tags (in which page authors can add keywords to help the search engines determine where and how to list and rank the page).

Noframes tags: Coding used to render text visible only to nonframes-capable browsers. A typical Website visitor therefore most likely would not see the text set off by the tags — but a search engine spider would, since most spiders can’t crawl frames.

Noscript tags: As is the case with noframe tags, coding used to render text visible only to browsers that are not using JavaScript. Again, a typical consumer most likely would not see the text set off by the noscript tags, but a search engine spider would.

Organic listings: Listings that appear on a search engine solely because of merit, applicability, etc. In other words, listings that are not paid for; also called natural listings.

Pagejacking: Stealing pages from other sites and using them as fodder for search engines.

Paid inclusion: Paying to be included in a search engine or directory index. Does not improve search rankings but guarantees inclusion of pages a spider might have missed and “respidering” of pages periodically. Also called pay for inclusion (PFI).

Paid placement: Paying for a link to be included on a search results page, usually at the top or right of the regular search results and set off by a label such as “sponsored links.”

Screen scraping: Capturing data from another company’s Web pages that weren’t meant to be viewed by outsiders; SEO spammers do this to determine coding patterns of competitors that they then use to try to outrank them on search engine listings.

Sneaky redirect: A Website directing a search engine spider to a page that is different from the page seen by site visitors. If a user clicks on a sneaky redirect page from a search engine, he will be redirected to a page different from the one described on the engine’s listing results. Most engines penalize or ban sites that use sneaky redirects.

XML feed: Simplified version of HTML that allows data (including product databases) to be sent to search engines in the format they request