Here's my brief explanation of electric guitar parts and what they do:
The headstock contains the tuning machines (also called machine heads), which are used for tuning a guitar.
The nut is a strip that lays on the border between the headstock and the fingerboard. It has small grooves for strings to pass over as they go through the fingerboard to the bridge.
The nut keeps strings at a proper height over the fingerboard, around the first frets.
The frets are the thin metal ridges on the fingerboard. Pressing a string down between the frets will change its tone.
The bridge does the same job as the nut on the other end of the strings. It's also responsible for correct pitch change over the pressed strings (called intonation) and transmitting the vibration of those strings to the guitar's body.
Many electric guitars have a spring-loaded hinged bridge called a whammy bar. I'll tell you more about whammy bars below on this page.
Fret markers are painted dots or other symbols around the 3rd, 5th, 7th, 9th, 12th, 15th, 17th, 19th, 21st and 24th frets (if your fingerboard is that long). Their only purpose is to help orientating around the fingerboard.
The magnetic pickup is a device containing magnets wrapped with coils of fine wire under each string.
They pick up physical string vibrations and convert them into electric fluctuations.
The Pickup switch allows you to shift and combine signals from the different pickups.
Combined with the tone and the volume knob, they provide the ability to tweak and modify the tone of the instrument.
The output jack is a slot for plugging in the guitar cable in order to connect it to an amplifier, guitar effects, recording interface, chromatic tuner and etc...
Despite of the word "electric", the vast majority of electric guitars do not have any active electronics on board. That's why the signal from the output jack is very, very small and requires amplification before being emitted from the speaker.
Hope there's no need to explain what are the body, neck and the strap pegs ;)
Note that parts of an electric guitar can look slightly different from one instrument to another, especially on hollow body guitars.
Click here to learn about differences between the solid and hollow body electric guitar.
The main difference in an electric guitar's structure is that not all of them have a whammy bar, (most of Les Paul guitars for example do not have these).
The whammy bar (also called a tremolo arm or vibrato unit) allows you to change the string’s tension on the fly by pushing or pulling on the lever attached to the guitar bridge, causing the pitch to change accordingly.
It gives a lot of possibilities to perform guitar tricks such as: diving into other note and coming back, make profound vibratos, vibrate whole chords and natural harmonics making your guitar roar and squeal.
Example of a whammy bar trick
So if you don't have a guitar yet and you're considering buying one, decide first if you'll need a whammy bar, because adding a whammy bar to a guitar that originally does not have one, could turn out to be horribly tedious work, with endless tweaking and tuning losses, and it'll will very probably compromise the tone.
If learning guitar with video lessons is a better idea for you I've found a few not bad videos on the basic subjects for beginners like: Parts of an Electric Guitar , String Directions, Tuning, Holding the Guitar and some more...