An abstract syntax tree (AST) is a data structure used in computer science to represent the structure of source code. It breaks down the code into its fundamental components, such as expressions, statements, and declarations, while ignoring specific syntax details like punctuation. This makes it easier for compilers and interpreters to analyze and manipulate the code. ASTs are essential in various programming languages, including Python, Java, and C++. They facilitate tasks like code optimization, error checking, and code generation. By providing a clear representation of the code's logical structure, ASTs help developers understand and transform code more effectively.