1. You can use one of the reserved words of c# with the @ symbol
string @int = "senthil kumar";
or something like this
string @class ="MCA";
Although you can use this , avoid using one.
2. Before a string specially when using the file paths .
You can use
string filepath = @"D:\SENTHIL-DATA\myprofile.txt";
string filepath = "D:\\SENTHIL-DATA\\myprofile.txt";
3. For a Multi lined text