Despite (or perhaps because of) their simplicity, CSV files are one of the most popular and widely used file formats. But what is a CSV file exactly, and how do you work with one? We go over all the answers below.

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What is a CSV File?

A CSV file is a plain text file that stores comma-delimited data in a tabular format. The abbreviation CSV stands for "comma-separated values."

The filename of a CSV file should always include the ".csv" extension. The structure of CSV files is as follows:

  • The (optional) first line in a CSV file is the "header" and contains the names of the file's columns.
  • The remaining lines in the file consist of records, one per line. Each record has one or more data fields separated by commas. (This means that the number of commas in each line should be 1 less than the number of columns.)
  • Line breaks separate individual records, i.e. with the newline character "\n" (which is ordinarily invisible when viewing the file).

Below is an example of a simple CSV file structure that contains a header and two employee records:

ID,LASTNAME,FIRSTNAME,EMAIL 268,Smith,John, 659,Public,Jane,

CSV files are a subclass of delimited text files in which the comma character "," acts as the delimiter. Other types of delimited text files may use other characters (e.g. tab characters, spaces, semicolons) as the separator.

Why Use CSV?

CSV files are a straightforward, lightweight method for storing relational and tabular data. Thanks to their simplicity and flexibility, CSV files have a wide variety of applications and benefits. CSV files are:

  • Easy to read: Unlike some other data storage formats, CSV files are easily readable by humans, as they store information in plain text.
  • Lightweight: These files have a small footprint. The only additional space they take up is the header row and the commas between each data field.
  • Portable and flexible: As we'll discuss later, it's easy to import CSV files into many other software applications.

Is There a CSV File Format Standard?

The CSV file definition we gave above basically covers everything you need to know about CSV files—but is there also a formal definition of the CSV file format standard?

The closest thing to a CSV standard is RFC 4180, which was written in 2005 by the Internet Engineering Task Force (IETF). However, this document is only for informational purposes, and it contains the disclaimer: "This memo provides information for the Internet community. It does not specify an Internet standard of any kind."

Below are a few quirks and details of the CSV file format, as described by RFC 4180, that you might want to know about:

  • The line break for the last line (record) in a CSV file is optional.
  • You can also optionally use double quotes (i.e. the " character) to enclose each field in a record. If double quotes do not wrap the fields, then the fields should not contain quotation marks.
  • Fields that contain commas must use double quotes. For example: Smith, John, "Peoria, Illinois".

Although RFC 4180 provides well-defined guidelines for CSV files, there's no guarantee that any particular file with the ".csv" extension will follow these guidelines. For example, Microsoft Excel uses semicolon delimiters for CSV files in European countries that use commas where English speakers would use decimal points.

How to Work with CSV

The simplicity of the format makes it fairly easy to work with CSV files. You can use a text editor like Notepad or a web browser to read them, and they are easy to import into a database or spreadsheet program (e.g. Microsoft Excel, Google Sheets, or OpenOffice Calc). You can also convert CSV to SQL if you want to store it in a relational database.

Most text editors and word processors can save a file in CSV format using the "Save As..." option. This makes CSV files compatible and interoperable with other basic file types such as XLS, TXT, and HTML.

However, there are still a few concerns to be aware of when working with CSV files. For example, what if you want to use special characters and formatting? According to the RFC 4180 specification, the "common usage" of CSV files is the US ASCII character set. But CSV files can also support alternate encodings such as Unicode character sets (e.g. UTF-8 and UTF-16)—as long as the application you're reading or editing them with supports these encodings.

How Can Help with CSV Files

Working with CSV files isn't difficult when you have only a few small ones on hand. But when you're storing large amounts of CSV data, it can quickly become unmanageable—and what if you want to transform and combine the contents of multiple CSV files for easier reporting and analysis?

That's where ETL (extract, transform, load) comes in. ETL is a data integration process that extracts information from one or more sources, applies needed transformations, and stores it in a centralized data warehouse or data lake. is a powerful, user-friendly ETL data integration pipeline with support for CSV files, databases, SaaS applications, and more. With over 100 pre-built data integrations and a simple drag-and-drop interface, you can build a robust, production-ready data pipeline to your cloud data warehouse.

See how can help integrate your enterprise data. Get in touch with our team of data integration experts today for a chat about your business needs and objectives, or to start your 14-day pilot of the platform.