Comma-Separated Values or Character-Separated Values (CSV) is a common "flat file database" (or spreadsheet-style) format for storing tabular data in plain text, with fields separated by a special character (comma, tab, etc). Rows are typically denoted by newline characters. Use for any delimited file formats, including tab delimited (TSV)
CSV is a file format involving a plain text file with information separated by delimiters with the purpose of storing data in a table-structured format. CSV (comma separated values) files traditionally and most commonly use a comma delimiter (hence the name), but other characters can be used, such as semi-colons, tabs, pipe symbols (|), etc.
The MIME type for CSV files is text/csv.
Information is often stored in CSV format to make it easy to transfer tables of data between applications. Each row of a table is represented as a list of plain text (human-readable) values with a delimiter character between each discrete piece of data. Values may be enclosed in quotes, which is required if they contain the delimiter as a value. The first row of data often contains headers of table's columns, which describe the meaning of the data in each column.
Example
Tabular format
| Time | Temperature | Humidity | Description |
|---|---|---|---|
| 08:00 | 70 | 35 | Sunny and Clear |
| 11:45 | 94 | 90 | Hazy, Hot, and Humid |
| 14:30 | 18 | Freezing | |
| 16:00 | -200 | "Unliveable" |
CSV format
Time,Temperature,Humidity,Description
08:00,70,35,Sunny and Clear
11:45,94,90,"Hazy, Hot, and Humid"
14:30,18,,Freezing
16:00,-200,,""Unliveable""
In this example, the first row of CSV data serves as the "header", which describes the corresponding data below it. There is no inherent way to describe within a CSV file whether the first row is a header row or not. Each successive line of the CSV file should neatly fit into the same field as the first line.
Note:
- Empty fields (fields with no available data, such as the third field in the last line) are place-held with commas so that the fields that follow may be correctly placed.
- Since the comma is the delimiter for fields, the commas in the Description field of the second line must be quoted (to prevent them from being interpreted as field delimiters). Wrapping the entire field in double quotes (
") is the default method for protecting the delimiter character inside a field. - Since the double-quote is the delimiter quote character, double-quotes in the data, as in "Unliveable" on the fourth line, must also be protected. Doubling-up the double-quote is the default method for protecting the quote character inside a field.
- If you are asking about a problem with correctly reading a CSV file, please provide the actual CSV file as text, not a table (and usually just a small snippet, big enough to demonstrate your problem but no bigger; see also the guidance for providing a minimal reproducible example).
- CSV files are suitable and natural for columnar data, but unsuitable for nested structures or other irregular data. Thus, questions about how to convert JSON or XML (etc) to CSV are often met with requests for clarification; only the most trivial JSON etc files can meaningfully be translated to CSV.
Questions tagged csv are expected to relate to programming in some way, for example, parsing/importing CSV files or creating them programmatically.
Related links:
- What to set as mimetype for csv files to open in spreadsheet applications
- RFC 4180 (describes official CSV format)
- CSV file checker
