Configuring Security in Salesforce

1. Object-Level Security (Permission Sets and Profiles):    
2. Field-Level Security (Permission Sets and Profiles):
3. Record-Level Security (Sharing):

1st and 2nd is related to Profile and 3rd is related to Role.

OWDs:
Organization-Wide Defaults, or OWDs, are the baseline security you for your Salesforce instance. Organizational Wide Defaults are used to restrict access. You grant access through below other means:

1. Sharing rules
2. Role Hierarchy
3. Sales Teams 
4. Account teams
5. Manual sharing

There are four levels of access that can be set:

1. Public Read/Write/Transfer (only available of Leads and Cases)
2. Public Read/Write
3. Public Read/Only
4. Private