I hadn't used these lines in my basic programs still i didn't get any errors, in which purpose we use them..?can anyone tell me

Question

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace something

Answer 1

If you tag the question c#, you might get more answers.
This is importing several standard libraries from .NET. You aren't going to get errors, if you don't use them. Static analysis tools will warn you about unused imports. Feel free to remove the ones you don't need.

Answer 2

thank you
Igor Berger