When a user enters a search query, the search engine matches the query terms with the terms in the index. The search engine then returns the documents or data objects that are most relevant to the query. The relevance of a document or data object is typically determined by the number and frequency of matching terms.
Indexing can be done manually or automatically. Manual indexing is the process of creating an index by hand, while automatic indexing is the process of creating an index using a computer program. Automatic indexing is typically more efficient and accurate than manual indexing, but it can be more difficult to set up.
There are a number of different indexing techniques that can be used, each with its own advantages and disadvantages. Some of the most common indexing techniques include:
* Keyword indexing: This technique involves identifying the most important words or phrases in a document or data object and adding them to the index.
* Phrase indexing: This technique involves indexing entire phrases or sentences instead of individual words.
* Stemming: This technique involves reducing words to their root form before indexing them. For example, the words "running", "ran", and "runs" would all be stemmed to the root word "run".
* Stop word removal: This technique involves removing common words, such as "the", "and", and "or", from the index.
The choice of indexing technique depends on the specific application. For example, keyword indexing is often used for general-purpose search engines, while phrase indexing is often used for specialized search engines, such as those used for searching legal documents.
Indexing is an essential part of information retrieval. By creating an index, it is possible to quickly and efficiently search for information in large collections of documents or data objects.