Transistors and Diodes both belong to the semiconductor family and both are used throughout electronic projects.
You do not need to know a lot about these two components other than you need to follow ESD rules, and
be careful that you don't get them too hot when soldering. The other thing is knowing how to tell on a
transistor which leads are which, and on a diode how to tell the anode from the cathode.
Figure 1 shows a transistor and it's Schematic Symbol. The three leads on a transistor are named, the Base, the
Emitter, and Collector. These will commonaly be shown as B,E, and C. The package that the transistor came
in will show which is which, and it goes without saying that it is very important that when you solder in
a transistor that you follow where the leads go.
Figure 2 shows a couple of diodes and their Schematic Symbol. A diode consists of two leads and they are
known as the cathode and anode. All diodes come with a "Band" which shows which end of the diode is the
cathode. In figure 2 above I have shown the bands and how they relate to the schematic symbol. Just make sure
when installing diodes that the band is placed in the correct direction.