Strings, in C#, represents text as a series of Unicode characters. A string can be referenced as both "string" and "String" - string is basically an alias of System.String. It can be created in a number of ways. In the simplest form, it can just be assigned or alternatively it can be created using the String's constructors. String, like other objects in .NET, can be assigned to null. Strings might look like and can be used like other variables like int or double but one important characteristics is that it is immutable - that is, once a String is created, it cannot be changed (so, when a string variable is re-assigned, behind the scenes, a new string is created and assigned to the variable).
Here is an example of different way of how strings can be created.