What properties self and scope stands for in Jira API requests?

[Nazar Vasylyshyn]

Hello! I don't understand why i need properties self and scope in api like: 

https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-projects/#api-rest-api-3-project-projectidorkey-statuses-get

and here is scope property: https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-projects/#api-rest-api-3-project-projectidorkey-get

Anybody know?