Difference between List,Set And Map in Salesforce

Hi Vikas,

A list is an ordered collection of elements that are distinguished by their indices. List elements can be of any data type—primitive types, collections, sObjects, user-defined types, and built-in Apex types.

A map is a collection of key-value pairs where each unique key maps to a single value. Keys and values can be any data type—primitive types, collections, sObjects, user-defined types, and built-in Apex types.

A set is an unordered collection of elements that do not contain any duplicates. Set elements can be of any data type—primitive types, collections, sObjects, user-defined types, and built-in Apex types.

Yes, you can use List of list but it depends on scenario to scenario which suits best for the functionality.

Hope this helps you.

Thanks