Why do we use abstract method when we can directly declare normally.i cant see the difference

Answer 1

This link can be pretty helpful:
https://www.c-sharpcorner.com/blogs/when-to-use-abstract-classmethods-instead-of-normal-classmethods-in-c-sharp

Answer 2

might want to might want to create cars, motorcycles, bicycles, trucks, and other kinds of machines like that, the abstract one to cover them say Vechiles could do so and we can create desired objects as from that base class. save us ever having to make them all just make the abstract base and all the subclasses can come from that.

a polygon isnt real its abstract but its subclasses shapes like triangle circle etc are real but they can all be subclass of the abstract base