Porn or pornography is a form of entertainment meant for sexual excitement. This can include videos, pictures, or literature. It is typically used by people in the case of self pleasure and partnered sex. Sometimes people use porn to educate themselves about sex but it should be noted that not all forms of pornography offer a realistic view of sex. It's always best to engage in ethical porn, one that not only depicts sex in a healthy way but prioritizes sex workers.
Sources:
https://www.healthline.com/health/healthy-sex/is-porn-bad#overview
https://www.britannica.com/topic/pornography