Search Engine
Any service generally designed to allow users to search the web or a specialized database of information. Web search engines generally have paid listings and organic listings. Organic listings typically come from crawling the web, though often human-powered directory listings are also optionally offered.
Search Engine Marketing
The act of marketing a web site via search engines, whether this be improving rank in organic listings, purchasing paid listings or a combination of these and other search engine-related activities.
Search Engine Optimization
The act of altering a web site so that it does well in the organic, crawler-based listings of search engines. In the past, has also been used as a term for any type of search engine marketing activity, though now the term search engine marketing itself has taken over for this. Also called SEO.
Search Terms
The words or word or key phrase a searcher enters into a search engine’s search box. Also used to refer to the terms a search engine marketer hopes a particular page will be found for. Also called keywords, query terms or query.
SEM
Acronym for search engine marketing and may also be used to refer to a person or company that does search engine marketing.
Rank
How well a particular web page or web site is listed in a search engine results. For example, a web page about seo may be listed in response to a query for “seo.” However, “rank” indicates where exactly it was listed — be it on the first page of results, the second page or perhaps the 100th page. Alternatively, it might also be said to be ranked first among all results, or 13th, or 121st. Overall, saying a page is “listed” only means that it can be found within a search engine in response to a query, not that it necessarily ranks well for that query. Also called position.
SEO
Acronym for search engine optimization and often also used to refer to a person or company that does search engine optimization
Shopping Search Engine
Shopping search engines allow shoppers to look for products and prices in a search environment. Premium placement can be purchased on some shopping search indexes.