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Puzzle pieces

Many puzzles are termed "fully interlocking", which means that adjacent pieces are connected so that they stay attached when one is turned. Sometimes the connection is tight enough to pick up a solved part by holding one piece.

Some fully interlocking puzzles have pieces of a similar shape, with rounded tabs (interjambs) on opposite ends and corresponding indentations—called blanks —on the other two sides to receive the tabs. Other fully interlocking puzzles may have tabs and blanks variously arranged on each piece; but they usually have four sides, and the numbers of tabs and blanks thus add up to four. Uniformly shaped fully interlocking puzzles, sometimes called "Japanese Style", are the most difficult because the differences in the pieces' shapes are most subtle.

Most jigsaw puzzles are square, rectangular or round, with edge pieces with one straight or smoothly curved side, plus four corner pieces (if the puzzle is square or rectangular). However, some puzzles have edge, and corner pieces cut like the rest, with no straight sides, making it more challenging to identify them. Other puzzles utilize more complex edge pieces to form unique shapes when assembled, such as profiles of animals.

The pieces of spherical jigsaw, like immersive panorama jigsaw, can be triangular-shaped, according to the rules of tessellation of the geoid primitive.

Designer Yuu Asaka created "Jigsaw Puzzle 29". Instead of four corner pieces, it has five. The puzzle is made from pale blue acrylic without a picture. It was awarded the Jury Honorable Mention of 2018 Puzzle Design Competition. Because many puzzlers had solved it easily, he created "Jigsaw Puzzle 19" which composed only with corner pieces as revenge. It was made with transparent green acrylic pieces without a picture.