User and Profile are required for using Salesforce application.
User :
A user is anyone who logs in to Salesforce. Users are temp/regular employees in your company, such as sales reps, managers, and IT specialists, who need access to the company's records.
Profiles:
Profiles determine what users can do in Salesforce.
Profile is simplest way to control data access on a particular type of object
This video will explain about
1. What is user and its required attributes
2. What is profile and how to create profile
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