If a shape matches itself perfectly when folded in half, it has line symmetry; if it looks exactly the same after a 180° turn, it has point symmetry. Two shapes that overlap perfectly are congruent.
If two shapes overlap perfectly when placed on top of each other, they're congruent. If drawing a line through the middle of a shape and folding along it makes both halves match perfectly, the shape has line symmetry, and that line is called the axis of symmetry. Neat shapes like a square are classic examples.
On the other hand, if you mark a point at the center of a shape and spinning it 180° around that point makes it match the original, the shape has point symmetry. Interestingly, some shapes have both line and point symmetry (a square), while others have line symmetry but not point symmetry (an isosceles trapezoid).
Don't just go by whether a shape "looks neat" — click the buttons and see for yourself whether folding or spinning it actually makes it match.