Atomic short-range order is mainly determined by the typical local bonding requirements of chemistry. For instance, substantial local atomic order is still present in fully amorphous materials such as silica glass: Each silicon (Si) atom is tetrahedrally surrounded by four oxygen (O) atoms at 1.62 Å, and the oxygen–oxygen separation is typically 2.65 Å. This phenomenon is call short-range ordering.

Atomic structure ordering in materials can be categorized by:
        i) Short range ordering (SRO).
        ii) Medium range ordering (MRO).
        iii) Long range ordering (LRO).

The atomic SRO structural organization is only composed of the nearest neighbour atoms. Both SRO and MRO are normally used to describe the atomic ordering phenomena in materials which are not in long range order. Pair Distribution Function (PDF) analysis is often used to study SRO in amorphous or crystalline materials.

Table 3101 summarizes the some basic differences between crystals, glasses, and liquids.

Table 3101. Some basic differences between crystals, glasses, and liquids.