There are three different approaches to Salesforce Implementation, listed below:
Big Bang Implementation
In this implementation process, old CRM users are transformed to a new Salesforce.org platform with components best suited for their business.
Phased implementation
In this implementation process, transformation to the new Salesforce.org environment is divided into several chunks. One chunk is focused at a time with all the processes followed respectively.
Parallel Implementation
In this implementation process, both new and old Salesforce.org platforms run simultaneously for some instances to maintain the continuity.