Territory Management is an account-sharing model that grants access to accounts based on the attributes of the accounts. It empowers your company to edifice your Salesforce data and business users the same way you manage your sales territories:

A territory is a collection of the account records and business users where the users have minimum read access to the accounts, irrespective of who owns the account records. By enabling territory settings, users can get read, read/write, or owner-like access to the accounts in that territory. Both users and accounts can exist in multiple territories. Salesforce allows you to add accounts manually to territories or define account assignment rules that assign accounts to territories for you. It also makes it possible to control users' access to the opportunities and cases related to the accounts in the territory, irrespective of who owns the records.

Salesforce's original Territory Management feature allowed you...