Information retrieval can be divided into broad sense and narrow sense. Information retrieval in a broad sense is called "information storage and retrieval", which refers to the process of organizing and storing information in a certain way and finding out relevant information according to the needs of users. Narrow information retrieval is the second half of "information storage and retrieval".
Usually called "information search" or "information retrieval", it refers to the process of finding out the relevant information that users need from the information collection. Information retrieval in a narrow sense includes three aspects: understanding the information needs of users, information retrieval technology or methods, and meeting the needs of information users.
According to the principle of information retrieval, information storage is the basis of information retrieval. The information stored here includes not only the original document data, but also pictures, videos and audio. First of all, these original information should be converted into computer language and stored in the database, otherwise machine recognition cannot be carried out.
After the user inputs the query request according to the intention, the retrieval system searches the database for information related to the query according to the user's query request, calculates the similarity of the information through a certain matching mechanism, and converts the information into output in descending order.
Information retrieval originated from the library's reference service and abstract indexing, and first developed in the second half of19th century. By the 1940s, indexing and retrieval had become an independent tool and user service project of libraries. With the advent of the first electronic computer in the world in 1946, computer technology gradually entered the field of information retrieval, and was closely combined with information retrieval theory.