Vanilla describes sexual interests, practices, or relationships that fall outside of kink and BDSM, typically centered on conventional intimacy like kissing, oral sex, and penetrative sex in positions that do not involve power exchange or sensation play. Someone who identifies as vanilla is not necessarily judgmental or inexperienced, they simply find their satisfaction in what most people would call mainstream sex.
The term comes from vanilla as a default flavor: plain, unadorned, but not boring to the people who prefer it. Plenty of people in the kink community use the word with affection rather than as an insult, and many kinky folks have vanilla partners or enjoy vanilla sex as part of a balanced sex life. It also functions as a useful shorthand in dating profiles so potential partners can set expectations early.
Also called: vanilla sex, vanilla relationship, vanilla partner, vanilla-friendly, non-kink, conventional intimacy