Electrical schematics are read from left to right and top to bottom. The circuit inputs are usually located at the top left, while the outputs are at the bottom right. You need to know the effects of individual circuit elements to understand the circuit function.
Each circuit element is assigned a unique symbol. Common symbols include a solid line for interconnects, zigzagging lines for resistors and a downward-pointing triangle or set of parallel lines that are successively shorter for ground. Ground represents the lowest voltage in a circuit, usually taken as a reference voltage.
Solid lines indicate interconnects between individual elements. These interconnects are wires in larger circuits, such as in the wiring diagram for a refrigerator. In smaller and more intricate circuits, these interconnects may be metalized pathways on a semiconductor microchip. Interconnects are generally considered ideal, having no resistance to the flow of electrical current, although the effects of interconnect resistance become more deleterious on the performance of the circuit as the total interconnect length increases. U-shaped protrusions or depressions when an interconnect passes another interconnect indicate that they pass over or under one another without connecting.
Resistors are another common circuit element, denoted by zigzagging lines or hollow rectangles. These circuit elements restrict the flow of current depending on their magnitude. Larger resistance means lower current flowing downstream of the resistor.