"What are you writing?"
Adding a "在" gives the present continuous tense of the sentence. "你写什么" would translate among the lines of "What do you write".
How frequently do native speakers omit 在 when indicating that an action is occurring? Do people make sure to use it in formal writing, but frequently omit it in casual speech, or something else?
It is not grammatically correct if you want to show that the action is taking place right now though. As it is, 'writing'
在 gives the continuous conotation "你写什么?" sounds more like "what do you write?" to me.
I'm kinda confused on when its appropriate to use 在, like does it indicate you're in the process of doing something? Why can't you just use the sentence without it in this example?