Format Odyssey

FILE FORMAT GUIDE

CSV File (.CSV): Import Columns Without Losing Meaning

A CSV file stores tabular records as text fields. A spreadsheet import can turn those fields into columns, but delimiter, encoding and number interpretation matter. Open it through an import preview instead of assuming that the filename guarantees comma separation or preserves every field's original type.

Check supported header evidence locally. Identification is not file validation or a malware scan.

Analyze a file locally

Quick facts

Extension
.csv
Format
Comma-Separated Values
Category
data
MIME type
text/csv
Standard / developer
IETF
Open with
LibreOffice Calc

What is CSV?

RFC 4180 describes a common comma-separated representation with an optional header. Fields containing delimiters or line breaks need quoting, and an embedded quote is escaped by doubling it. Spreadsheet import settings can change how dates, numbers and leading zeros are interpreted; CSV itself does not store a workbook's cell formatting.

  • Exchange rows and columns between applications
  • Import or export spreadsheet table data

How to open CSV

LibreOffice CalcDesktop spreadsheet

Use File > Open and select Text CSV when necessary. In the import preview, choose the correct character set, field separator and string delimiter. Set identifier columns to Text to retain leading zeros. For untrusted data, leave formula evaluation disabled and inspect the preview before importing.

Technical details

Signature
No registered magic number
Encoding
Producer-dependent; choose the appropriate character set during import
Container
Not reviewed
Compression
Not reviewed

RFC 4180 — common CSV representation (Informational)

Things to check

  • Spreadsheet exports do not preserve cell formatting in CSV.
  • Import settings affect number conversion and whether formulas are evaluated.

Related formats

Sources & review

Fact review: 2026-09-18. Unknown fields are not inferred from the file extension.