Fields are the building blocks for structured content. The type and order of the fields that you add to a content type decide how the content will be finally presented. For instance, while creating a content type for a “News Article” page, you may add fields such as "Title," "URL,"' "Date," "Body," as seen in the following screenshot:
All the content you will be adding to create an entry goes into fields.
Note: You can add at the most 100 fields in a particular content type.
Fields are of various types, designed to handle the most shared content input needs. Each field type determines the type of data it can store. An example of a field type is the Number field type, which accepts only numeric characters. Similarly, there are several other types of fields that you can use in a content type.
Each field possesses specific properties, such as “Display Name,” “Unique ID,” “Default Value,” “Help Text,” “Mandatory,” and so on. These properties are editable, providing flexibility to customize the nature of the field.
Additional Resource: You can check out the Field Properties section to learn how you can use and set them for a particular task.