arsers are everywhere in programming world now: JSON, XML/HTML, routes.rb mapping language, Regular expressions, HTTP headers. Mainly because the best way to pass data from one app to another is stringifying data on one site and parsing on another. It is a matter of time when you would need to create parser yourself. This talk is all about Parsers and how they work. It starts from theoretical aspects of parsers, goes to practical example for simple tasks and finishes with live examples of how parsers inside ruby and rails works.