Marketing is the key to success, and marketers know that concept sells. There are notable exceptions, of course, but each production company is looking for something for their particular market. I'm not asking you to sell out, I'm only asking you to acknowledge reality as you seek a screenwriting career. Here's a few quotes I've heard from Hollywood types. When I hear a good concept, I immediately see a movie.
Concept comes in many forms.
The concept could come in the form of a logline . The logline is the TV Guide one-sentence version of your story. Whatever form your concept takes, it will become the core of your pitch. And pitching is another Hollywood reality. Your query letter is actually a written pitch, and your pitch should be rooted in a strong story concept.