CSV — Comma-Separated Values
CSV is the simplest tabular data format: plain text where each line is a row and commas separate the columns. Values containing commas or line breaks are wrapped in quotes. That's the whole format — which is exactly why every database, spreadsheet, analytics tool and programming language supports it.
CSV carries data only: no formatting, no formulas, no types beyond what the consuming application infers.
What CSV files are used for
- Exporting and importing data between systems
- Database dumps and bulk uploads
- Data science and scripting workflows
- The common denominator when two tools share no other format
Advantages
- Universally supported, human-readable, easy to generate and parse
- Compact and streams well for large datasets
- Diff-able and version-control friendly
Limitations
- No types: leading zeros, dates and large numbers are easily mangled on import
- One table per file — no multiple sheets
- Delimiter and encoding ambiguity (semicolon vs comma, UTF-8 vs legacy) causes real-world breakage
How to open a CSV file
Spreadsheet apps open CSV directly, but importing carelessly can mangle dates and leading zeros. For working with the data in Excel, converting CSV to XLSX first gives you a proper workbook from the start.
Frequently asked questions
Is a CSV file the same as an Excel file?
No. Excel opens CSV files, but a CSV is plain text: rows of values separated by commas or semicolons, with no formatting, formulas or multiple sheets. An Excel file (XLSX) is a full workbook. Converting CSV to XLSX gives you a proper workbook that keeps its columns.
Why does my CSV open in one column in Excel?
Because the file's delimiter doesn't match your computer's regional settings. In Brazil, Spain, most of Europe and many other regions, the comma is the decimal separator, so Excel expects semicolons between columns. A comma-separated file then lands in a single column, and the reverse happens elsewhere. Converting the CSV to XLSX avoids it: Filembly detects commas, semicolons, tabs and pipes automatically.
Does CSV use commas or semicolons?
Both are common. The name says comma, but spreadsheet apps in regions that write decimals with a comma (1,5 rather than 1.5) export CSV with semicolons instead. Tabs and pipes (|) also appear in exports from banks, stores and accounting systems.
Why do accented letters look broken (é, ç) when I open a CSV?
The file is UTF-8, but Excel read it with an older character set. Importing it through Data → From Text/CSV and choosing UTF-8 fixes it, as does converting it to XLSX. Filembly reads both UTF-8 and older Windows-encoded CSV files, and the CSVs it exports include the marker Excel needs to show accents correctly.
How do I open a CSV file?
Any spreadsheet app opens it: Excel, Google Sheets (File → Import), LibreOffice Calc or Numbers. Any text editor shows the raw values too. To keep leading zeros, long ID numbers and dates intact in Excel, import the file rather than double-clicking it, or convert it to XLSX first.