usability - Best placement for a "Go Back" button: top or bottom?

I know that it is bad practice to use a "Go Back" button (since the browser has such a function) but when it can't be avoided for some reason, is it better to put it on top (similar to how the back buttons on browsers are on top) or at the bottom (similar to "cancel" buttons on forms)?

Let's say the page is not a form but rather a "Preview" / "View" page of some sort where user can view data.

Answer

Top-left seems to be the ideal position for the "Back" button due to the following reasons:

1. All traditional and modern PC browsers have it there. There is almost no learning curve.


2. This would seem much more native on tablets than mobile. But you will have an advantage of efficient scaling up of UI since Back button won't change its position across different platforms. And users will be at ease while shifting among them. Since, tablets come closest to the PCs in terms of screen size, consistency among them comes handy sometimes and users don't feel too out of place (particularly the ones who are moving to tablets from laptops or such).


3. Most applications have it on top-left. Consistency across applications for similar elements is always good for the users. Also, I would suggest it be a floating kind of a button particularly if your screen contains scroll-able content.

Top-left would not be ideal if your app is not native and will run in a browser window which has its own controls on the top. Then, it would be ideal to place the said button on bottom-left.

In any case, it's always a best practice to avoid such buttons on right side of the screens since traditionally, they are much more suitable for forward kind of functions and not backward (which a "Back" button is for).

Also, you said that it's a preview kind of screen, then I would suggest you use a text button like "Close Preview" or something which is much more descriptive and to the point.