You do a 5k.
Maybe a 10k, maybe not.
Probably more 5k races are thrown in.
Then, there's your first half marathon run.
This is the natural progression of things, for a runner. Next comes the marathon distance. For most runners, it is the top tier of running goals.
Among these, the largest jump is by far from 13.1 to 26.2 miles. Even if you're training for a 5k, you're probably completing runs of 10k or longer. Heck, even for a half marathon more advanced athletes will likely run the distance or at least the time the race should take them, during training.
This is not the case with the marathon.
When thinking about your first marathon, there are steps and considerations to be mindful of.