Profiles, permission sets, and object security
Profiles define how users can access data and the whole Salesforce application.
There should be one profile per user and one license type per profile – easy to remember. Also, more than one user can share the same profile.
Your organization comes with standard profiles that (there are exceptions for some Salesforce editions, such as contact manager, group edition, or essentials edition), you can customize a few permissions for on a standard profile or clone (creating a new custom profile) so that you have full access to its customization (for example, custom object access, field-level security access). The only thing you cannot change is the license type related to a profile.
Permission sets are similar to profiles with a simple difference: you can assign zero or more permission sets to a single user, thus providing additional capabilities that are not set up in the base profile. This increases permissions attribution granularity when creating simple profiles with few capabilities and granting users different powers as needed (sometimes, a Salesforce user can have both sales and service capabilities, but you don’t want to create a profile with both permissions).
You may ask the following question:
“Can I use custom profiles only, instead of permission sets?”
You definitely can, but only if your users have clear permission needs and their operative role in the CRM is well defined, which is usually not the case. The business can ask for the sales representatives to be able to access and edit cases, though some service agents may be required to edit opportunities, which are a sales representative’s unique permission. If you have to take into account any exceptions when setting up permissions, you would end up with tens of custom profiles, a task that can be time-consuming. Instead, you should deliver some base and exclusive profile configuration and provide a class of permissions using permission sets to specific users when needed (a user can have only one profile but can be related to multiple permission sets).
To see what features are available in profiles and permission Sets, please refer to https://help.salesforce.com/articleView?id=permissions_about_users_access.htm&type=5.
You can edit a profile with two different interfaces: the enhanced profile user interface and the original (or standard) profile interface.
To enable the Enhanced Profile User Interface, click on Setup | Users | User Management Settings and enable the Enhanced Profile User Interface flag:
Enabling the enhanced profile user interface
This interface is a more powerful profile editing page that supports all the settings that are provided by the original interface: the main enhancement is the capability to search for settings as opposed to the original interface, where all the main options are in a single page. To switch from a master setting to a child one, you need to browse different pages.