What Is a CSV File? A Plain-English Guide for Beginners
CSV stands for comma-separated values. It is the simplest way to store a table, and almost every tool can read it.
A CSV file is plain text. The first line holds the column names and each next line is one row, with the values separated by commas. For example: id,name,marks on the first line, then 1,Ada,92 and 2,Alan,88 on the next two. If a value contains a comma, it is wrapped in quotes.
You can open a CSV in a text editor, in Excel or Google Sheets, or in code, for example pd.read_csv("file.csv") in Python. Excel sometimes changes values on opening, for example it may drop leading zeros from codes such as 00123 or reformat dates. Converting the file or importing it as text avoids that.
CSV is not the same as Excel. A CSV holds one table of text with no formatting, formulas or several sheets, so it is small and easy to move between systems. An Excel file can hold formatting, formulas and many sheets. Use CSV to exchange data, and Excel to work on it by hand.
To try it, generate a sample CSV below, open it in a text editor to see the raw text, then convert it to Excel, JSON or Parquet with the Format Converter and compare the files.
Everything runs in your browser and nothing is uploaded.
Related tool pages
- JSON to CSV Converter: Convert JSON to CSV in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
- CSV to JSON Converter: Convert CSV to JSON in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
- CSV to Parquet Converter: Convert CSV to Parquet in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
- JSON to Parquet Converter: Convert JSON to Parquet in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded.
- Parquet to CSV Converter: Convert Parquet to CSV in seconds. Drop a file or paste data and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
- Parquet to JSON Converter: Convert Parquet to JSON in seconds. Drop a file and download the result. Private: it runs in your browser and nothing is uploaded. Large files too.
How to use the Format Converter: step by step
- Generate a sample CSV.
- Open it in a text editor and read the raw text.
- Open it in Excel or a viewer.
- Convert it to another format and compare.
When to use the Format Converter
- Understand what a CSV is
- Open a CSV without Excel changing it
- Choose between CSV and Excel
- Move data between tools
Example
Input: id,name,age 1,Ada,36 2,Alan,41
Output: [{"id":1,"name":"Ada","age":36},{"id":2,"name":"Alan","age":41}]
Frequently asked questions
How big can a file be?
It depends on your device. A few hundred MB usually works.
Which conversions does the Format Converter support?
Any direction between JSON, CSV, Parquet and Excel (.xlsx), for one file or a whole folder. Nested JSON is flattened into columns such as address.city. For Excel, the first sheet is read; old .xls files are not supported.
Why did my number or date change after converting?
Types are detected from the values. Turn off "Detect types" to keep everything as text, which also keeps leading zeros in IDs and phone numbers.
Tip: If Excel drops leading zeros, import the column as text or convert the file instead of double-clicking it.