In Salesforce, it is the Governor Limits which controls how much data or how many records you can store in the shared databases. Why? Because Salesforce is based on the concept of multi-tenant architecture. In simpler words, Salesforce uses a single database to store the data of multiple clients/ customers. The below image will help you relate to this concept.
multi tenant architecture - salesforce interview questions
To make sure no single client monopolizes the shared resources, Salesforce introduced the concept of Governor Limits which is strictly enforced by the Apex run-time engine.
Governor Limits are a Salesforce developer’s biggest challenge. That is because if the Apex code ever exceeds the limit, the expected governor issues a run-time exception that cannot be handled. Hence as a Salesforce developer, you have to be very careful while developing your application.
Different Governor Limits in Salesforce are:
Per-Transaction Apex Limits
Force.com Platform Apex Limits
Static Apex Limits
Size-Specific Apex Limits
Miscellaneous Apex Limits
Push Notification Limits