Final answer:
Permission sets were introduced in Winter '12 release of Salesforce platform. They are used to grant additional permissions to users who already have a profile assigned to them.
Step-by-step explanation:
Permission Sets Released in Winter 12
Permission sets were introduced in Winter '12 release of Salesforce platform. They are used to grant additional permissions to users who already have a profile assigned to them. These sets can be used to grant extra permissions to specific users or groups without modifying their profiles.
Permission sets can be created and assigned based on the specific needs of the users. They provide a granular level of control over object access, field-level security, tab visibility, and record-level permissions. This allows administrators to tailor permissions based on different roles within an organization.