Motherboard is a non-conductive plastic sheet that has the necessary circuit and placeholders like sockets/slots to connect components and provide logistics for all the components to work in a coordinated manner. It is a chassis in which all the components are fitted in the designated place and they are all powered and well interfaced with each other.
Motherboards are present in Desktop, Laptop, Tablet, and Smartphone and the components and functionalities are the same. There are 6 types of motherboards. In the next section, they are briefly explained.