Difference between analog and digital ground?

[pradhan.rachit]

Hello all,

I recently came across a circuit which had separate analog and digital grounds. What is the difference between both of them? Also they had mentioned not to connect both of them together. What problem will it cause if I connect them together?
Also, even if i don't connect them together, won't the ground reference mismatch cause problems in the operation of the circuit?

Looking forward for your replies
Thank you.

 

[rahul.achates]

A very good explanation -

**broken link removed**