A programming language is a formal set of instructions that allows humans to communicate with computers. It provides the syntax and semantics needed to write code, which can be executed to perform specific tasks. Examples of popular programming languages include Python, Java, and C++. Each language has its own rules and is designed for different types of applications, from web development to data analysis. Programming languages can be categorized into high-level and low-level languages. High-level languages, like JavaScript, are more abstract and easier for humans to read and write, while low-level languages, such as Assembly, are closer to machine code and offer more control over hardware.