Difference between default access profile,owner access profile and book access profile

Hi All,

  I recently had some discussions with my friends and have some major doubt on my understading of access profiles (default/Owner & Book). Appreciate if you could throw some light on these 3 access profiles, when each one will come into play & which will take max precendence.

Other Queries

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1.When a user is not assigned to any books then will default access profile come into play?

2.Will default access profile come into play only when "Can read all data" is checked for a particular object in Step 2 of role management?

3.When will book and default come into play and between deafult and book which takes highest precedence?