Reference type

Reference type is .Net framework type that stores the address of their data, also known as a pointer, on the stack. The actual data to which that address refers is stored in an area of memory called the heap.
Different with Value type, assigning one reference variable to another doesn’t copy the data. Instead, assigning a reference variable to another instance merely creates a second copy of the reference, which refers to the same memory location on the heap as the original variable.