If you need help resolving a problem, you can grant login access to your account to a Salesforce administrator or a support representative.
By default, your company’s administrators can access your account without any action from you. If your organization requires users to grant login access to administrators, you can grant access for a specified duration.
For security reasons, the maximum period for granting access is 1 year. Once you granted access, administrators or support representatives can use your login and access your data to help you resolve problems.
If an administrator, support representative, or publisher makes setup changes using your login, the setup audit trail lists the changes and the username.
In some organizations, records of clicks made by an administrator logged in as you are also kept for auditing purposes.
NOTE: If your administrator has restricted access to certain support organizations, you can’t grant access to these organizations. Packaged application licenses can also prevent access.
This information is very useful to administrator to grant the login access to Salesforce administrator or support.