Permission sets are the last feature we will look at to open up access. You use permission sets if you have a group of users that all have the same profile but there is one person that needs extra access for a business reason. It would not make sense to create a whole other profile for just one permission. Permission sets allow you to add a single permission to the user's record, letting you bypass creating a whole new profile for one additional setting.
Permission sets
A business use case
You are the Salesforce admin for XYZ Widgets. The sales manager has requested for a certain sales team lead to be able to modify all accesses to Opportunities in order to edit all the opportunities for their team. You do not want to...