I've started lear solidity and have some simple questions:

1. Why sometimes in contract people write _varname, but not varname?

2. In remix i can execute inline function (function a() { b=4; } ) why? Function isn't external or public

3. If byte32 use less gas than string, why people use string?

Thanks

I've started learning solidity and have some simple questions:

1. What is it that in contracts people write _varname, but not varname?

2. In remix, I can execute inline functions like (function a() { b=4; } ) Why is this possible as the function isn't external or public?

3. If instantiating a variable of type byte32 requires less gas than of type string, why do people use strings?

Thanks