Is there a back button in iPad?

No, there isn't. Individual apps have their own back buttons. But there is no global back button.

To go back to a previous app place four fingers on the right side of the screen and pull to the left.

That *****

*Stinks

Thanks! It works!

Back to where?

In Safari there is a back arrow which will take you to the last page you visited.

Other than that, most apps implement the back button on their own based on their needs.

You're welcome.