petstore-oas-get-query-simple-v1.yaml

paths:
  "/pet": 
    get:
      parameters:
        - in: query                               # defines the query parameter that should be sent which is the category id
          name: categoryId                        
          schema:
            type: integer
            example: 1
          required: true
          description: category id to fetch pets for
      tags:
        - Pet
      summary: Get all pets based on category id
      responses:                                      
        200:                                    # define the response based on a success condition
          description: Success
          content:
            application/json:                   # this shows that response is a JSON object
              schema:
                type: array                     # returns an array 
                items:
                  $ref: "#/components/schemas/Pet"    # refers to the pet schema defined earlier