CSV (Comma-Separated Values) to JSON (JavaScript Object Notation) conversion is the process of transforming data from a CSV file format into a JSON format. CSV is a simple text format for tabular data, while JSON is a lightweight data-interchange format that is easy to read and write for humans and machines. Converting CSV to JSON is useful because JSON is often used in web applications and APIs due to its structured and hierarchical nature, making it easier to handle and integrate with modern programming languages and frameworks.