What are the major types of schemes in Jira?

Issue type scheme: Helps in establishing the relationship between the available issue types and the project. It offers the assurance that correct screens are utilized for every issue type.

Field Configuration Scheme: It allows you to configure the schemes as you wish. For every field, You can specify whether it is the required field.

Workflow schemes: Graphic shows the configuration of the workflow and its scheme. A workflow helps in defining the sequence of steps that can taken in the project.