Pink sand is found most commonly on tropical beaches adjacent to coral reefs. The pink colouration comes from red foraminifera, single-celled marine organisms with reddish shells, commonly found on coral reefs but also among sand, rocks and plants at the bottom of the ocean.
When the organism dies, the shell is ground up by wave action and some of that debris will mix with fine particles of calcium carbonate from shells and corals to give the beach a pink tinge.
Rather than the fairy-floss pink that your mind might conjure up, beaches famed for their pinkness are likely to exhibit a blush rather than a full-throttle, cherry blossom pink.
Another source of pink sand is the vivid kind seen on social media images, tinted that way by Instagrammers indulging in a moment of extravagant fantasy. The fakery is especially prevalent in images from the Bahamas, don't go with high expectations unless you're wearing rose-coloured specs.
In our own region the Indonesian island of Komodo has its own Pink Beach but beware, there be dragons.