To Facebook someone is to use the website Facebook to look them up, send a message, or stay in touch. People turned the brand name into a verb: “I’ll Facebook you,” “She was Facebooking old classmates.” It is informal. In careful writing, keep the capital F, because it is still a company name. Though actually, among some younger people the word already sounds a little dated — they may live on Instagram or Threads instead — but Facebooking is still understood. In Taiwan people still usually say 臉書 for that site, even after the company took the bigger name Meta.

上臉書、用臉書查人／聯絡（台灣口語仍多叫「臉書」）