Parsing is an age-old technique used to analyze and extract meaning from languages (both natural and programming). Parser is a type of compiler that converts the stream of text into syntax or parse tree that conforms to some predefined grammar rules.
There are various classifications to categorize these techniques, and plenty of content is available to explain them. So, for now, I am focusing on Parser Expression Grammar (which is the most recent research in parsing grammar). Also, I will try to explain the ways to implement a PEG parser.