# What does “Tag Integer is Protected” message mean?

(Newbie question)

For every function I define I get this message:

When I close and reopen Mathematica, and re-enter the function definition, I don't get the message anymore. What does it mean?

-
You can see that f is already defined because it's coloured black. You can verify this using ?f too. Instead of the drastic Remove[f] you can also use Clear[f] to clear all definitions, or f =. to remove f's value if f is a simple variable (in Mathematica terms: it only has OwnValues but not DownValues). – Szabolcs Jun 13 '12 at 7:29
@Szabolcs - Thanks again. I should have known better than to use a single letter as a function or variable name :-/. But this was meant to be a quickie :-) – stevenvh Jun 13 '12 at 7:31
You may find this discussion of some relevance. – Leonid Shifrin Jun 13 '12 at 9:00

It means you set f = 156 sometime before you executed that function definition. Executing a Remove[f] before your new definition should have fixed the problem.