A CSV (Comma-Separated Values) file is a plain text file format commonly used for storing tabular data. It is a simple and widely supported file format that represents data in a structured manner.

Each line in a CSV file typically represents a row of data, and the values within a row are separated by commas or other delimiters, such as semicolons or tabs. Each value can be a string, a number, or any other data type. The first line of a CSV file often contains headers that describe the data in each column.

CSV files are widely used for data exchange between different applications, databases, and spreadsheet software. They can be easily created, edited, and read using various tools and programming languages. An MS Excel application for example will open a CSV file, and convert it to a .xls or .xlsx file format.