A screenwriter writes screenplays for films and television shows. They are responsible for dialogue, timing, and shooting scripts. Screenplays can be written speculatively with no payment promised or commissioned by a producer. Most screenwriters start by writing speculative scripts freelance. They may also sell treatments or synopses of unfinished work. More established writers are more likely to succeed this way. Screenwriters sometimes gather work by rewriting other scripts or adapting existing works like books into screenplays. In America, the Writers Guild of America helps represent screenwriters.