The definition of the term lexical is derived from the word "lexeme" in lexical analysis. In linguistics, a lexicon is an abstract morphological element. There are many stages or passes in the compiler. Each phase is significant, but the parser plays a critical part in the compilation process. Text editors, information retrieval systems, pattern recognition algorithms, and language compilers all make use of lexical analyzers. A lexical analyzer, lexer, scanner, or tokenizer is a program in the compilation step that does lexical analysis. The lexical analyzer is used in a variety of computer science applications, including word processing, information retrieval, pattern recognition, and language processing. The goal of this paper is to the operation of a lexical analyzer in the most direct way possible in order to give in-depth understanding of the lexical analyzer phase.