A parser is a software component that interprets and processes input data, typically in the form of text or code. It breaks down the input into manageable parts, allowing the system to understand its structure and meaning. This is essential in programming languages, where a parser converts source code into a format that can be executed by a computer. In the context of web development, a parser can analyze HTML or XML documents to extract information or transform data. For example, a web scraper uses a parser to gather data from websites, while a compiler uses a parser to translate high-level programming languages like Python or Java into machine code.