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Glass holds a special place in physics: it is not a crystalline solid and it is not a liquid.
A crystal is made of atoms which are arranged in a unit cell. This unit cell is repeated in all three directions. This order is retained over long atomic distances: it is referred to as long range order.
A liquid on the other hand lacks this order: the atoms are not rigidly bound to each other and they "flow" in the material. A liquid has no order.
Glass is an amorphous or non-crystalline solid: it is in a state between the crystalline state and the liquid state. It does not have the long range order of crystals but it is not a liquid either. The atoms in the glass are bound to each other but they lack the long range order. However locally they can be ordered and possess a short range order.