Half steps and whole steps form Major scales.
When two keys are pressed one after another (melodically) and no key is skipped, the distance or interval is a half step.
When two keys are either pressed one after another (melodically) and exactly one key is skipped, the distance or interval is a whole step.
I have illustrated this with the three simplest Major scales: C Major, F Major and G Major.
Note: I have included the key signatures for the F Major and G Major scales, for those who are familiar with key signatures. However, I have not yet covered key signatures, so I included a flat and a sharp in parentheses, to help relative beginners.