I think it also called a "pantster." Writing by the seat of the pants. I do a combination of both planning and pantster. Most of my short fiction, I just start with an idea and let it develop. But I usually have an ending in mind.

I have written some longer stories that I just started writing and the story revealed itself. But I can't imagine writing a novel without an outline. I started my novel with a bare-bones outline: beginning, end, and some ideas for the rest. But the outline grew as I wrote. It kept me on track to reach the ending.