How do Matrix Shards work and where can I find them?

Solution 1:

Three shards can be combined using an Assembler to form a Matrix Cube; the cubes are then used in your character's Relics slots. There found on all the planets and only in datacrons.

As far as the number, there are 67 datacrons. However, there are a limited number of shards to be found (3 red, 3 yellow, 3 blue, 2 green--98% sure, again).

Here's a video walkthrough with more details on how to use them:

This is the most comprehensive guide I could find on the locations of the datacrons (including those with shards):

http://www.republictrooper.com/datacron-locations/

Solution 2:

A pretty comprehensive guide on how to get the datacrons themselves with screenshots and a walkthrough for each, broken down by planet:

http://www.swtor-spy.com/datacrons/

Same site has a guide on the assembly as well:

http://www.swtor-spy.com/guides/matrix-cube-guide/1047/

Have only been able to confirm Empire side guides thusfar, but, found them to be very accurate.

Not saying that this site is definitely better, but, I personally found it clearer to follow.

Solution 3:

What I found on google and it worked for me:

http://www.cyberneticpunks.com/matrix-cubes-guide-how-to-make-them/

It has info on the blue matrix shard and other shards. There was also a datacron guide in there