Tell me, ajax hash, what is it for?

Question

PHP

For example, VKontakte attaches a hash to each ajax request. I mean, when an ajax request is sent to the server hash, for example 8828962ff4f29bae20 What role does it play? Why is it needed at all? Here is an example from VK:.
6b6be3aa994fd8a85e - hash that is passed to...

Answer 1

I remember it used to be in vogue among fake 'ers to open an iframe on VK, or rather a logout link ... well, I think whoever understood understood what I was talking about ... Until VK began to attach a hash to almost every link and in general any action. Then the iframe was banned altogether. And on your question, I can only say that hash is needed to protect against illegal actions. That is, the same hash is attached to a specific user.
Banal example: In the mobile version of VK, as a rule, all actions are performed through href elements . Whether it's joining groups, likes and adding friends. Now imagine if VK removed its elementary security methods for a day. What do you think, how many subscribers to the group and to my page would I have by the end of the day ???))

Answer 2

Probably CSRF protection

Answer 3

protection against CSRF, as well as to update the url without reloading like site.rf/#a31sgdg1545...

Answer 4

To change page uri without reloading. There is no html5 history api on older browsers, and hashes are simpler.