Difference between callback methods and virtual methods

[Sagala_lahari]

Hii, May I know the difference between the virtual methods and callback methods and what is the usage of those methods in System verilog with examples?

[dave_59]

Callbacks in system verilog and uvm

can someone explain me callbacks?i have gone though the vmm central site,i couldnot understand.please with some simple example explaination is required