A DataFrame is a two-dimensional, size-mutable, and potentially heterogeneous tabular data structure commonly used in data analysis. It is part of the pandas library in Python and allows users to store and manipulate data in rows and columns, similar to a spreadsheet or SQL table. Each column can hold different data types, such as integers, floats, or strings. DataFrames provide various functionalities, including data filtering, aggregation, and merging. They are designed to handle large datasets efficiently, making it easier for data scientists and analysts to perform operations like data cleaning and transformation. This versatility makes DataFrames a fundamental tool in data science and machine learning.