Role Hierarchy :
If we add a user to a role, the user is above in the role hierarchy will have read access.
Setup ? manage users ? roles ? setup roles ? click on ‘add role’ ? provide name and save.
Defines the baseline setting for the organization.
Defines the level of access to the user can see the other user’s record
OWD can be Private, Public Read Only, Public Read and Write.
Setup ? Security Controls ? sharing settings ? Click on ‘Edit’
Manual Sharing :
Manual Sharing is sharing a single record to single user or group of users.
We can see this button detail page of the record and this is visible only when OWD setting is private.