The principle is simple: if there is a paid or otherwise material relationship between a creator and what they are promoting, the audience has a right to know. That covers sponsored posts, free products in exchange for coverage, affiliate commissions, and brand-ambassador deals. Vague tags buried in a wall of hashtags do not count — disclosure must be clear and hard to miss.
Best practice is a plain label placed up front: "#ad," "paid partnership with [brand]," or the platform's built-in paid-partnership tool, plus a spoken disclosure in video. Beyond legal compliance, clear disclosure protects audience trust — and audiences increasingly expect transparency, so hiding sponsorships tends to backfire when discovered.