diatonic chords

can someone explain what is a diatonic and put some examples pls?

Diatonic is basically the major scale (and modes)... A scale which has five tones (whole steps) and two semi-tones (Half steps).

C, D, E, F, G, A, B, C

Whereas the Chromatic scale uses every note.

Well, if something is diatonic that means that it is within the key. For example, the key of C major contains the notes C, D, E, F, G, A, and B, so all those notes are diatonic. Eb would not be diatonic to the key of C major. By extension, chords are diatonic if they are comprised entirely of diatonic notes, however, usually when people are talking about diatonic chords they're talking about diatonic triads (2 thirds stacked on top of each other, so three notes, hence the name). In the key of C, the diatonic chords are C major, D minor, E minor, F major, G major, A minor, and B diminished. Here's why, using the C major chord as an example: So we've got C, D, E, F, G, A, and B that are diatonic notes, and we want a diatonic triad built on C. Since triads are 2 thirds stacked on top of each other, we just go a third up from C, which is E, and then go a third up from E which is G. C minor is not diatonic because it contains Eb instead of E which is not diatonic to the key of C major.

Hope that helps a bit.

EDIT:
Actually, looking back at what you asked, I think I may've explained a little bit too much. :P

haha, well explained though.

@foogered:
thnx for the explanation, i really understood it...(is not sarcasm)
@jazz:
Thnx u 2, now it's a lil bit more clear to me...

I wouldn't worry about it too much. Charlie Parker always said: "Learn them then forget them"

Meaning learn the names, understand what they do, and then forget the names and it becomes second memory. Awesome to be honest.

yeah i know what u mean jazzy...just wondering about what r them...but now im clear...so thnx...and yeah...that thinking is awesome and very functional XD