Final answer:
The two common motherboard standards are ATX and microATX, with ATX being the most prevalent and designed for a variety of enclosures, while microATX is a smaller version allowing compact system builds.
Step-by-step explanation:
The two common sets of motherboard standards are ATX (Advanced Technology eXtended) and microATX. The ATX standard is the most prevalent form factor and provides specifications for the dimensions, power supply, and mounting points. It is designed to improve the overall system integration and to suit various types of enclosures. In contrast, the microATX standard is essentially a smaller version of the ATX standard, which allows for smaller system builds without sacrificing too much in terms of performance and expandability. Both standards are maintained by the same organization, which ensures that they maintain compatibility with each other, hence allowing parts from both standards to be mixed and matched to a certain degree.