SF Backup and Restore Overview

It is important for Salesforce customers to develop a routine data backup strategy as part of their overall data management and security model.  

It is important to understand the differences between data types (data and metadata) and what is included in each backup method:

Data refers to all of your records, including Accounts, Contacts, Leads, Opportunities, Cases, Contracts, and other records. Data also includes your custom object records, files, content, and Chatter.

Metadata refers to all of your configuration settings, such as custom fields, page layouts, Reports, Dashboards and custom code like Apex and Visualforce.

Best practices to backup Salesforce data