whats the difference in sd card classes?

[Sam Trevor]

Hi
looking at buying some more sd cards.
Could someone please explain what the difference is between the classes.
cheers
Sam

 

[scottthehat]

this will help.
http://en.wikipedia.org/wiki/Secure_Digital

 

[TheNissanMan]

It is the speed at which they can read/write data. Don't automatically assume this will enable you to take more shots on continuous shooting as some camera's will be limited by the buffer.