What is Globle setting connectionString?

In Globle setting connectionString is directly coding in web.config file.
Step 1
In web.config file adding three things.

1. add name="abc"
2. "Data Source=Raksha
3. Initial Catalog=st
4.  Integrated Security=true"

Step 2
In Default. aspx.cs file adding
using namespace:

string mystr = ConfigurationManager.ConnectionStrings["abc"].ConnectionString;

Output