Dataloader :-

Dataloader use for integration ( Insert,Upsert,Delete and Export ) data from external machine ( file should be an CSV ).

7 ways( function buttons ) :-

Insert :- Inserting data from external machine
Update :- Updating existing record
Upsert :- Insert and update record
Delete :- Deleting data ( recoverable )
Hard delete :- Deleting ( not recoverable )
Export : Taking out the data from our Salesforce.com
Export all :- All data extraction

Governor limits in Salesforce:-

Gov limits are run-time limits which is enforced at the time of Apex runtime.
Apex runs in a shared, multitenant environment the Apex runtime engine strictly enforces a number of limits to ensure that code does not monopolize shared resources,

Types of limits that Apex enforces are:

1)Memory
2)Database resources
3)Number of script statements to avoid infinite loops
4)Number of records being processed