A search engine is a technology that allows users to quickly and accurately find the information they need by collecting, organizing, Indexing, and retrieving information on the Internet. Search engines could search for information on the Internet based on keywords, categories, tags, links, and other factors, and display the search results to users. A full-text search engine is a search engine that can search the entire text document (such as novels, articles, papers, etc.). In the full-text search engine, the user can enter the text content that needs to be searched, and the search engine will convert the text content into characters and search. Unlike local search engines, full-text search engines usually display the search results of the entire text document so that the user can have a more comprehensive understanding of the required information. Spaces and double quote marks play an important role in full-text search engines. Spaces can be used to separate different sections to make the search results easier to read and understand. Double-quote marks are usually used to quote text to display the correct quote in the search results. In addition, double quote marks could also be used to mark citations, annotations, references, and other related information in the text.