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 and tools, including compilers, interpreters, and static analysis tools. They help in optimizing code, performing type checking, and generating machine code. By providing a clear representation of the code's logic, ASTs facilitate better understanding and processing of programming languages.