Audio Systems: Vinyl Recording

Question
How is sound recorded to a vinyl disc as I cannot understand how bumps can be
interpreted as sound. Surely there must be electricity encoded or something.

Answer
Here's a few articles that can explain this 100 times better than I can...

http://electronics.howstuffworks.com/record-player3.htm
http://blog.makezine.com/archive/2010/02/how_vinyl_records_are_made.html

As far as "bumps into sound" is concerned, here's some more links:

http://communication.howstuffworks.com/analog-digital1.htm

No electricity is needed actually. The electricity (besides turning the turntable) is strictly for amplifying the sound. If you put the needle to a record and turn the amp all the way down, if you put your ear near the needle, you'll be able to hear the content.

Sound is nothing but waves in the air. Those waves will make things "vibrate" - your eardrum, your house (with loud sounds like thunder), microphone diaphragms, etc...
Conversely, things that "vibrate" will disturb the air around it and create sound , like your speaker cones moving.
Those "bumps" on a record are only analog representations of the recorded sound. They aren't heard as such until the "bumps" are played at a specific speed. What the record needle is doing is "riding" in the groove of the record, and moving one way or the other (+ & -). That movement is turned into an electrical signals, sent to an amplifier, out to the speakers, and the + & - info is fed into the speakers, the cones move, and you once again have sound.