A schematic diagram is a representation of an electrical circuit, showing the electrical relationships using abstract graphic symbols rather than realistic pictures of components.
There are some components that schematics commonly include: voltage, ground, resistors, diodes, light emitting diodes (LED), switches, relays, capacitors.
A transistor includes three connections: a base, a collector and a emitter. It can work as an amplifier and a switch.
In schematics, to show a junction point, draw a dot at crossing.
Review on schematics components mentioned above.