Component Symbols
Electronic schematics are diagrams that describe the way electronic components are joined together in circuits. There are many different types of electronic components, and each type has a different symbol. Resisters are symbolized by a jagged line, for example, and most capacitors by two parallel lines.
Listing Components
A single circuit can have thousands of components in it, so it is often seen as impractical to give each component a number and letter and list its value on a separate list. So the first resistor in the circuit would be labeled "r1," the third capacitor C3 and so on. A sheet would list the values of all the components by type so you could easily look up the value of a particular capacitor or resistor.
Making Connections
The components in a circuit are usually joined by circuit traces. For most circuits, it doesn't really matter if two components are right next to each other or not, or what shape the circuit trace between them has. Therefore, electronic schematics simply show that two components are connected by connecting their symbols with a straight line. If many components are all connected together, there will be overlapping lines that attach to all the individual components.
