This is a security feature that helps protect your application from fake subpages.
Example:
Suppose you have a registration function in your web application. You have an AccountController (somename.com/account/register) where you expect people to submit their information. Usually, before someone submits registration information, you need to visit the actual (somename.com/account/register) than submit the form.
, , , , , - (somename.com/account/register) . , , AntiForgeryToken, , , .
: (http://www.binaryintellect.net/articles/20e546b4-3ae9-416b-878e-5b12434fe7a6.aspx)