Thais across the country offered alms at temples to celebrate the 88th birthday on Saturday of King Bhumibol Adulyadej, the world's longest-reigning monarch.
Some also sang, holding lit candles, outside the window of the King's hospital room in Bangkok.
Thais were swathed in yellow - their traditional colour for Monday, the day the monarch was born - and homes, offices and streets were decorated with his image.
King Bhumibol, whose last public appearance was in early September, has spent most of the last six years in Bangkok's Siriraj Hospital, due to poor health.
He is the only king most Thais alive today have ever known and widely revered, many even ascribing divine powers to him.