A new puzzle appears here every day, with three difficulty levels and a hint if you need one. Yesterday's and the day before's are there too, so a missed day is not a lost one. Puzzles are Shredder's daily tactics puzzle, shown here from their website.
Today's puzzle
More puzzles
If you get the taste for it, Lichess has an unlimited supply, free, and adjusts the difficulty to you as you go. There is more on the chess puzzles page.