YAML is a popular, widely used human-readable format for writing configuration files. It is the abbreviation for YAML Ain’t Markup Language. It is the standard format of serialization language used and written in various applications with different structures to transfer data to each other. The other groups are XML and JSON, and among these, YAML is considered the most straightforward and the cleanest format. The human-readable format is based on line separation and spaces with indentation. YAML is written through .yaml and .yml extensions, which are likely the same, but not entirely. 

Rules in Writing YAML File

The YAML file is written like the Python-style indentation in order to know the nesting. Whitespaces are used for indenting instead of tab characters, and this type of format doesn’t use any symbols such as square brackets, closing tags, braces, or even quotation marks. The YAML files only stick with their extensions which are .yml and .yaml

In addition, YAML carries scalars (arbitrary data encoded in Unicode) that are useful in typing values such as integers, dates, strings, numbers, etc. There is more to learn about writing YAML files. Understanding the basic concepts of YAML is the first step for beginners to practice the appropriate way of programming. 

The structure of a YAML file is either a map or a list.

The maps help in associating the key-value pairs because each key must be distinct. Nonetheless, the order of it doesn’t bear much. In creating a YAML map, the document should be finished first before closing it and starting a new one. You can create a new map by increasing the indentation level or closing the older map and starting an adjacent map. 

Meanwhile, a YAML List comprises values listed in a specific orderly way and can be inserted into a map. The sequence starts with a dash (-) then a space to separate the context from the parent. This list is similar to the Python list or an array in Bash or Perl. 

In creating a YAML file, following the syntax rules is highly essential. The file should also be valid. The Linter is an application that can vary the syntax of a file. Meanwhile, the yamllint command ensures that the YAML is valid before handing it over to the application.

Advantages of YAML File

Although YAML is a new format, a bit case sensitive, and most of us are still learning its curve. This text document shows off some great qualities that attract programmers. Here are the few advantages of using YAML  as your new data format:

  1. The text data are understandable and easy to write
  2. The format is lightweight
  3. It is pretty ideal for configuration settings
  4. It has no language barrier, so it supports a wide range of programming languages. 
  5. The data is easy to modify or edit
  6. And the complex mapping is simple enough to represent

Since the YAML format is language-agnostic, YAML files can be arranged within programs written in different languages that support YAML libraries like C#, C/C++, Java, Ruby, Perl, Python and PHP. Similar to the YML file, this file is used for defining the settings of a program or application. Plus, the .yaml is used to read and write data independent of a specific programming language. 


The YML extension is text document data in the format of YAML. This extension can be arranged into programs written in programming languages such as Python, Java, Perl, C#, C/C++, PHP, Javascript, etc. Commonly, YML files are used as configuration files that elaborate the application’s settings or its program. 

When a program uses a YML file in its settings, the program can be edited by opening the text or source code editor and modifying the YML file. There are ways to know how to adjust the program’s settings in a YML file and most settings include the guides in editing them. The .yml format allows the users to edit .yml files with content independent from any particular markup language. 

In order to open a YML file on the PC, a correct and compatible application will help to access the .yml file. There are cases where the correct application is not matched with the .yml files. Thus, it is important to purchase the right programs for your PC. 

The main objective of the developers in creating the YML file is to produce efficient data serialization. 


The .yaml and .yml are both extensions of YAML (YAML Ain’t Markup Language). Both offer similar interpretations and syntax. However, questions about their differences are piling up, and some users are confused about which one to use. The major difference between the two is that the older versions of Windows only allowed three letters in the extension, such as .yml. Meanwhile, the OS system now doesn’t have restrictions for the number of letters. That’s why some users prefer .yaml. 

On the other hand, there are yaml users who like to write faster. Thus, they pick .yml since it has fewer characters, the extension is 25% faster to write. Some users say that the Extensions do not have a bearing at all on the content. The only consideration is those Windows Programs that still have restrictions on the number of characters and they opt to limit the characters into three alone.

Generally, YAML creators prefer users to use the new 4-character extension (.yaml) since most Operating Systems allow more than three characters in the text document. However, programmers still use the (.yml) because it is faster to write. Another difference between the two extensions is Docker commonly uses .yml while Kubernetes’ documents .yaml.

Leave a Reply

Your email address will not be published.