Unlike Android, the iPhone doesn't have a dedicated "back" button. But, a little-known gesture makes that completely acceptable. In Messages, Mail and even Safari, simply swipe right from the edge of the screen to go to the previous window. The gesture even works in some third-party apps like Instagram.
Why there is no back button on iPhone?
It is because there is a swipe to go back feature where you can go back just by swiping your screen from left to right. If you are uncomfortable with that, iOS provides a back button on upper left corner in its default apps. The back button. Swipe to go back.
Does iPhone have a back button like Samsung?
The iPhone does not have a dedicated back button. It's an unnecessary waste of space. If an app needs a back button, it's built into the app. If the app doesn't need a back button, that's space the app can use for something else.