I've been tipped off to explain all this time signature stuff to people. I myself am a drummer as well as a guitarist, and find myself using this terminology all the time. To some people it might seem like gibberish, but i'll give a good try at explaining things here. Ever see people conversations involving terms like "7/8" or "5/4"? Thats what this is about.
Quite simply the bottom number stands for the note duration. 4 means quarter notes, 8 means 8th notes, 16 means 16th notes. The top number stands for the amount of those notes. The time signatures stand for your pulse. Most music is in 4/4 (common time). Everyone is used to it, you can count 1 2 3 4 along with it with no problem. But once someone gets really into rythm ideas, they may see theres a completely vast array of possibilities involving timing.
2nd in typical-ness (ha) is 3/4 time. This is really what makes a Waltz a Waltz. Its as simple as 1 2 3 1 2 3 1 2 3 etc. With me so far? Its just the amount of rythmic time that goes by for each bar or measure.
Now we get into an enterely new and fascinating world when we start thinking of odd numbers to put on top. Why not 5? Why not 7? Why not 9? Why not 11? Why not 13? As you can see the possiblities are vast. It may be kind of hard to teach people to play in a time signature such as 5/4 because our minds are so trained to hear and play in 4/4 all of the time. But give it a try. All you need to do is feel a pulse of 5 notes, repeating over and over. Put on a metronome, and instead of acting like its 1 2 3 4, listen to it as 1 2 3 4 5 instead. Now try playing to it? Pretty hard at first? Once you get used to how it FEELS it wont seem so hard. Try the same thing on the metronome with 7/4. Every bar here would be 7 beats so hear the metronome as 1 2 3 4 5 6 7, repeating over and over.
I guess the simplest way to try to get the feel of them would be (well use 7/8 as an example here) to pick 7 notes, and play them over and over but without a pause between them. 1 2 3 4 5 6 7 1 2 3 4 5 6 7 etc. If youve made it this far your already playing 7/8 time.
These are just a small amout of the possiblities. What about 9/8? 1 2 3 4 5 6 7 8 9. 11/8? 1 2 3 4 5 6 7 8 9 10 11. Etc. Etc. Etc. You can string any amount of notes together if you put your mind to it.
Once someone understands the concept thats going on here it doesnt seem so much like a secret code language now does it? I wish i would have some sound clips to demonstrate the different feels of the time signatures but im rather busy with things right now (i have to turn in a piano piece at college today). Someone might be thinking "how could i use this stuff...why would i use this stuff?". Well do you like stuff like Dream Theater
or any other Progressive stuff? Its jam packed with odd time signatures so you might have to get used to it to play the music properly.