Nonograms are picture logic puzzles. Every row and column has a short list of numbers, and by working out which squares those numbers allow, you fill in the grid until a picture appears. Every puzzle here can be solved by logic alone, with exactly one answer.
Reading the clues
The numbers beside each row and above each column are the lengths of its runs of filled squares, in order. A clue of "3 1" means a run of three filled squares, then at least one empty square, then a single filled square.
A 0 means the line is completely empty. When a line’s filled squares match its clue, the numbers turn pale so you can see what is left to do.
Filling and crossing out
Tap a square to fill it, and tap a filled square to clear it.
Long-press a square, or switch the tool under the board to Cross, to mark a square you know is empty with an X.
Drag along a row or column to fill or cross many squares in one stroke. The square you start on decides what the stroke does, so starting on a filled square clears instead.
On a computer, right-click crosses, and you can play with the arrow keys plus Space, F and X.
Start with the big numbers
Large clues give the most away. In a 10-square row with a clue of 7, the run must cover the middle four squares wherever it sits, so you can fill them straight away. A clue that adds up to the whole line, like "4 5" in a 10-square row, fixes every square.
Lines with a 0, or clues that are already complete, tell you where to put Xs.
Work back and forth
Each square you fill or cross gives new information to the line running the other way. Go back and forth between rows and columns, using what you just learned, until every line is finished.
You never need to guess. If you are stuck, look for a line where the squares you already know leave only one way to place its runs.
Sizes, timer and records
5×5 is a quick warm-up, 10×10 is the classic size and 15×15 is a longer puzzle.
The clock starts with your first move. Undo takes back your last move, and your puzzle is saved if you leave.
Some puzzles are hand-drawn pictures and the rest are random patterns. Best times are kept separately for each size.
On a phone, pinch a 15×15 board to zoom in.