Electronic symbol
An electronic symbol is a pictogram used to represent various electrical and electronic devices or functions, such as wires, batteries, resistors, and transistors, in a schematic diagram of an electrical or electronic circuit. These symbols are largely standardized internationally today, but may vary from country to country, or engineering discipline, based on traditional conventions. Standards for symbols. The graphic symbols used for electrical components in circuit diagrams are covered by national and international standards, in particular: The number of standards leads to confusion and errors. Symbols usage is sometimes unique to engineering disciplines, and national or local variations  to international standards exist. For example, lighting and power symbols used as part of architectural drawings may be different from symbols for devices used in electronics. Common electronic symbols. Symbols shown are typical examples, not a complete list. Traces. The large dot signifies an electrical connection. Grounds. The shorthand for ground is GND. Optionally, the triangle in the middle symbol may be filled in. Resistors. It is very common for potentiometer and rheostat symbols to be used for many types of variable resistors, including trimmers. Diodes. Optionally, the triangle in these symbols may be filled in. Note: The words anode  and cathode typically aren't part of the diode symbols. Bridge rectifiers. There are many ways to draw a single-phase bridge rectifier symbol. Some show the internal diode circuit, some don't. Transistors. Optionally, transistor symbols may include a circle. Note: The pin letters B/C/E and G/D/S aren't part of the transistor symbols. Relays. Note: The pin letters aren't part of the symbols. Lamps. LED is located in diode section. ICs. Logic gates. For the symbols below: A and B are inputs, Q is output. Note: These letters are not part of the  symbols. There are variations of these logic gate symbols. Depending on the IC, the two-input gates below may have: 1) two or more inputs; 2) infrequently some have a second inverted output too. The above logic symbols may have additional I/O variations too: 1) schmitt trigger inputs, 2) tri-state outputs, 3) open-collector or open-drain outputs (not shown). Flip-flops. For the symbols below: Q is output, is inverted output, E is enable input, internal triangle shape is clock input, S is Set, R is Reset (some datasheets use clear (CLR) instead of reset along the  bottom). There are variations of these flip-flop symbols. Depending on the IC, a flip-flop may have: 1) one or both outputs (Q only, only, both Q & ); 2) one or both forced inputs along top & bottom (R only, S only, both R & S); 3) some inputs may be inverted. OpAmps. Note: The outside text isn't part of these symbols. Historical electronic symbols. The shape of some electronic symbols have changed over time. The following historical electronic symbols can be found in old electronic books / magazines / schematics, and now considered obsolete. Capacitors (historical). All of the following are obsolete  capacitor symbols.