Is a woman's caressing of her private parts considered a forbidden form of masturbation, and what is the ruling on that?

A woman touching her vulva from the outside for the purpose of lust (masturbation) is forbidden. Masturbation is defined as expelling semen without intercourse, and it applies to both men and women, occurring even with a barrier. If touching the vulva from the outside is for the purpose of seeking pleasure, it is forbidden. However, if it is not for the purpose of seeking pleasure and ejaculation, it is not forbidden. The proof for this is the hadith "It is but a part of you," which indicates the permissibility of touching the penis in situations other than urination.