Adverbial intensifiers help establish the modality of a text - the degree of certainty, possibility or obligation - so adverbs are very powerful. Talking of whether an event might happen, we might say: possibly, perhaps, certainly, definitely, inevitably, absolutely, etc.
Modality is also established by verbs (might, must, should, could, etc), nouns (the possibility, the certainty, the inevitability) and adjectives (possible, probable, certain).
If you think of weather forecasts, you will get the idea of modality. The level of certainty about whether or not there might be rain varies from forecast to forecast. A forecast one day might predict a high probability of thunderstorms in the late afternoon. Another day the forecast might say that the weather will be fine until the weekend.
Deciding on the appropriate level of modality is an important part of academic writing, report writing, etc. A news report or police report on an accident might mention the possibility that an accident was caused by faulty brakes, the probability that it was caused by faulty brakes or the fact that it was caused by faulty brakes.