Human: I'm trying to play music by ear, can you tell me what musical scales to use? Assistant: 
The primary scales you should focus on are major, minor, chromatic, and pentatonic. Major and minor scales can be used in a variety of different genres, and the chromatic scale is great for learning how to play in a specific key. Pentatonic scales are great for blues and rock music, and can be very useful in many other genres, such as jazz and folk.