Updated 2026-10-14
What Is CSV File Format? (RFC 4180 Explained)
CSV (Comma-Separated Values) is a plain-text file format for tabular data, defined by RFC 4180.
Why CSV Matters
CSV is widely used for data exchange between systems because it is simple, human-readable, and supported by almost every spreadsheet and database program. Its simplicity makes it ideal for exporting and importing data without proprietary formats.
RFC 4180 Rules
RFC 4180 specifies that each line in a CSV file is a record (row). Fields within a record are separated by commas. If a field contains a comma, double quote, or line break, it must be enclosed in double quotes. Double quotes inside a field are escaped by doubling them (""). The last field in a record must not be followed by a comma.
Common Pitfalls
- Missing quotes around fields with commas, causing extra columns.
- Inconsistent quoting (some fields quoted, others not).
- Using a delimiter that appears inside data without proper escaping.
- Line breaks within fields without quoting.
- Assuming all CSV files use UTF-8 encoding (they may use other encodings).
Tools to Help
When working with CSV files, you can use tools to view, clean, convert, or validate them. NoCodeCSV offers several free utilities that run in your browser.
Try a CSV viewer
Upload a CSV file to see its structure, check for quoting issues, and verify delimiter usage — no installation required.
Frequently asked questions
What does CSV stand for?
CSV stands for Comma-Separated Values. It is a simple file format used to store tabular data, such as spreadsheets or databases.
Who defined the CSV format?
The CSV format is defined by RFC 4180, published in October 2005 by the Internet Engineering Task Force (IETF).
Do I need quotes around fields that contain commas?
Yes. According to RFC 4180, if a field contains a comma, double quote, or line break, the field must be enclosed in double quotes, and any double quotes inside the field must be escaped by doubling them.
Can CSV files use delimiters other than commas?
While the term CSV implies commas, many tools allow other delimiters like semicolons, tabs, or pipes. However, strict RFC 4180 compliance requires a comma delimiter.
Related reading
Related reading
CSV Fundamentals — other guides that pair well with this one.
Browse all guides in the NoCodeCSV blog.