I asked in my studies build a "sealed " class and I don't really understand it's differents from regular class and what different in syntax it has

Thanks Sergey

a sealed class is a class that uses encapsulation. All its fields (properties) are private, as are all its methods.

It cannot be used or modified from any other class.

if you think of a normal class, you have say a form, you can add to it. You can make it your own, you can extend it..

A sealed class you cant, its as it is, it cannot be tampered with. To make it sealed, you simply add the word sealed as a moderator at the front.

Thanks to all,
Yes I tried now to build one that reached from
two others and in Main() I get that it doesn't know about any method in it so I can use it

What do you mean by that?
C# doesn't support multiple inheritance like C++.
And I really don't understand your problem with "sealed".
Sealed is as it says : "sealed". Even me, as a non native english speaker can understand the word.

No I know that C# work not like C++,
My class reach from one and his Parent byself child from another one,
II don't know why I can't see methods of my sealed class if methods are public ?

Perhaps you need to do some reading and research

yes i mde so and now it brought to me other
question and useful instruments
I discover that class can be abstract and
override
override I understood that one method use Parents same method but "abstract" is still a question for me

then you need to read more

"ithen you need to read more"

it's what I already done and after that I ask for help here
if I not mistaken it's purpose of this forum