Let’s go with the practical:

There are 3 types of Variables in the Azure Pipelines which you can use of:

Variable Type 1: Defining the variable and value in variables section

variables:
- name: yamlvar
  value: "Iam YAML Variable"

Variable Type 2: Defining the variable and value in Run section

Steps: Click on “Variables” > Add the Variable and Value by clicking on + Sign and Save.

Variable Type 3: Defining the variable and value in Library — Variable Group section

Add New Variable Group and List available here

Properties of VG

Note*: These are only defining variables. Calling them to use is different and will be published in another article with simple form of understanding.*