The inseparable prefix ver- is the most common prefix in German, and it’s also one of the most confusing ones for learners because there just doesn’t seem to be a “system” to how it changes the base verbs.
But there actually is.
Ver- goes back to an ancient Indo-European syllable *per-, and the core idea of this syllable was
going beyond (a boundary)
We can put all the various ver-verbs into four groups, each of which is about a different kind of boundary crossing.
Here they are:
(from one state to another)
verbessern – to improve
verlängern – to prolong
verwirren – to confuse (to en-tangle)
(from “being here” to “being gone”)
vergessen – to forget
verbieten – to forbid
verstecken – to hide (“to stick away”)
3. wrong, mistake
(from “right” to “wrong”)
sich verschreiben – to make a typo
sich verlaufen – to get lost walking
(from one to another)
versprechen – to promise
vertrauen – to trust
Many verbs work with more than one idea and sometimes, ideas can overlap. verlieben for instance is to fall in love and we can think of it in terms of “for” but just as well in terms of “change”. Or even mistake, if it goes badly.
But yes, these are the four themes and they’re the key to pretty much all ver-verbs you’ll ever see.
Oh by the way… if you look at the examples here again, you’ll see a couple with “pro-” and “for-“. That’s no coincidence because in fact, pro-, pre-, for(e)- and per- all come from the same root and we can find the exact same themes in them.
For an in-depth look at this with lots of examples, this two part series on YourDailyGerman is a good resource: