What is Salesforce data security model?

Hi
To provide a security model that satisfies numerous, unique real-world business cases, Salesforce provides a comprehensive and flexible data security model to secure data at different levels. Salesforce also provides sharing tools to open up and allow secure access to data based on business needs.
Salesforce provides three layers of security with lots of flexibility to accommodate virtually any business need. Profiles controls object-level and field-level access. Permission sets are used to provide access to additional objects. Field-level security controls provide access to individual fields within an object.