If I use a protected variable, does the variable exist for the whole web application or does it get removed when the user move to other page by get or post? I do know that it is not accessible in other pages unless I use static variable, but I am curious as to if it exists for the whole application. Please let me know!
when you move to other page and return, a new instance of your page class will be created and so all non static variables will be reset.
The value will be valid in a one request process life time (starts with request start and ends with request end)
making a variable protected, just means that this variable is access-able in inherited class. for example in asp.net you can use it in inherited class like inside your markup (because it inherits code behind class)
this is the meaning of protected variable
if you want to keep a value saved between pages you can use one of these items depending on your requirement :
and ViewState keeps state variable between postback in a same page or control while it is not redirected to another page.