An index file is used by a search engine to locate specific web pages in a web site. The structure of an index file is similar in concept to the index of a book where keywords are referenced to their occurrence on pages. The performance of a search engine is heavily influenced by the quality of the algorithm used to produce the index. Writing a good quality indexing algorithm may seem trivial but in practice it isn't.

alphabetical listing of all words that have been used in a given field. Unlike an authority file, index files are compiled after content has been entered into the associated fields. see also Database Field see also Authority File

acnuc databases are made up of a series of index files that allow efficient accesses to sequence files according to various retrieval criteria. Index files are ACCESS, AUTHOR, BIBLIO, EXTRACT (not for protein databases), KEYWORDS, LOCUS, LONGL, MERES (optional, serves only to allow quicker launch), SHORTL, SPECIES, SUBSEQ, TEXT. Acnuc index files are always located in a directory whose name is given by environment variable acnuc.

A cross reference file showing property owners' name and parcel number which may also include other pertinent cross-reference information by parcel number.

A file created by a search indexer program, designed to store information in a format that makes fast retrieval possible.

Most FTP directories have this special file. the Index file is a list of what information is contained in each file on that particular computer. Think of an Index file like the index at the back of a book, telling you where in the book to go to find out about a particular subject or to find out the definition of a particular word.

Search engines creates this file, they collects data from your web page and store in their database for quick reference.