Here are some... Masturbation is a process of fulfilling pleasure-seeking from within in privacy; once one experiences its resultant gratification which is then ingrained in mind. As to its being good or bad, that hinges on if its consequence affects one's energy & ability for survival, growth, & continuation. If yes, it is bad; if not, okay. Remember: overindulgence & obsession are the most common chronic killers.
Neither good nor bad. Normal men, women, boys, and girls masturbate (it's universal). It is not harmful, as the body goes through similar effects during regular sex with a partner (but too much of anything may become a problem). Masturbation does not stunt height, cause acne or hair loss, make you weak, create heart problems, lower testosterone, affect virginity, lower fertility, change your weight, or damage vision.