OWD for Standard Objects in New Org

The default organization-wide sharing settings for Standard Objects are:

Object Default Access
Account Public Read/Write
Activity Private
Asset Controlled by
Parent
Calendar Hide Details and Add Events
Campaign Public Full Access
Case Public Read/Write/Transfer
Contact Controlled by Parent
Contract Public Read/Write
Custom Object Public Read/Write
Lead Public Read/Write/Transfer
Opportunity Public Read Only
Price Book Use
Service Contract Private
Users Public Read Only
Private for external
users

Public Full Access:
This option is available for setting the Campaign object only along with other access options. Through public access the user can have the ability to search records, reports, add related records, edit details of the records and can delete the record.
When the Campaign object is set to public full access, all users in that organization can be able to view, edit, transfer and delete.

Public Read/Write/Transfer:
This option is available for Leads and Cases objects only along with other access options. When lead or case objects are set to public read/write/transfer, then all users can view,edit, transfer and report on all the case and lead records.

Public Read/Write:
Whenever a record is set to public read/write the user can view, edit and report on all the records.

Public Read Only:
When a record is set to public read-only the user can search the records, view and report on every record but the user cannot edit that record. Only record owners and assigned users can edit that records.

Private:
When a record is set to private only that record owner and users above that role in an hierarchy can view, edit and report on those records.