Are all squares rectangles, or are all rectangles squares? Help me!

Square is a subset of rectangle, so all squares are rectangles. However, not all rectangles are squares. Rectangle can have incongruent adjacent sides, but square must have congruent adjacent sides.

https://math.okstate.edu/geoset/Projects/Ideas/SquareRect.htm

Quadrangles are all four figured shapes including regular (with names like square and parralelogram) and irregular with all different length sides. (satguru)
http://www.dictionary.com/browse/quadrangle

All squares are rectangles. A rectangle has four right angles. However, not all rectangles are squares. A square does have four right angles, but the sides must also have the same measurement. So, only some rectangles are squares.