1.2. Full text search

Recoll is a full text search application. Full text search applications let you find your data by content rather than by external attributes (like a file name). More specifically, they will let you specify words (terms) that should or should not appear in the text you are looking for, and return a list of matching documents, ordered so that the most relevant documents will appear first.

You do not need to remember in what file or email message you stored a given piece of information. You just ask for related terms, and the tool will return a list of documents where these terms are prominent, in a similar way to Internet search engines.

A search application tries to determine which documents are most relevant to the search terms you provide. Computer algorithms for determining relevance can be very complex, and in general are inferior to the power of the human mind to rapidly determine relevance. The quality of relevance guessing is probably the most important aspect when evaluating a search application.

In many cases, you are looking for all the forms of a word, not for a specific form or spelling. These different forms may include plurals, different tenses for a verb, or terms derived from the same root or stem (example: floor, floors, floored, flooring...). Search applications usually expand queries to all such related terms (words that reduce to the same stem) and also provide a way to disable this expansion if you are actually searching for a specific form.

Stemming, by itself, does not accommodate for misspellings or phonetic searches. Recoll supports these features through a specific tool (the term explorer) which will let you explore the set of index terms along different modes.