What types of World Wide Web search engines are there?

The main body of World Wide Web search citation is full-text search engine, and the most representative full-text search engines are Google, AltheWeb, AltaVista, Inktomi, Teoma, WiseNut, Baidu, HC, etc. The tools used for searching in the World Wide Web are called search engines, which can be divided into two categories: full-text search engines and classified directory search engines.