TO USE GLOBAL PARAMETER FROM WEB.CONFIG FILE

Below mention is code to access Connection string from Web.Config file. Here you can have multiple variables.

Write this in Web.Config file :

<configuration> 

  <appSettings> 

     <add key="ConnectionString" value="server=localhost;uid=sa;pwd=;database=DBPerson" /> 

  </appSettings>

</configuration>

//Here value is Connection String used to connect with database

 Now you can access above value in your web page as given below: 
using System.Configuration;
string connectionString = ConfigurationSettings.AppSettings["ConnectionString"].ToString();


Note:Similarly you can add multiple KEY which you want as global variable.