This blog is a small step to amalgamating the different aspects of Salesforce Security Model by displaying how Record Access is defined in an org. This security model is an important area to understand while building a Salesforce application.
**Please note that these info are consolidated from various Salesforce webinars so that some important concepts can be tracked at a single place in a lucid manner. This could be primarily helpful for the beginners to have a 360 degree view of security settings.
So, referring the image below, the approach should firstly look at the foundation which is Object CRUD(controlled by Profiles) and then move upwards following horizontally through OWD, Role Hierarchy, Sharing Rules, Manual Sharing, Apex Sharing.
**Please note that these info are consolidated from various Salesforce webinars so that some important concepts can be tracked at a single place in a lucid manner. This could be primarily helpful for the beginners to have a 360 degree view of security settings.
In Short or At a Glance, you can refer the below two images.
Please note that these info are consolidated from various SFDC webinars so that the important concepts can be tracked at a single place.
Happy Salesforce.com Evangelism.. 
