Since heat is a result of the molecules motion of an object and this motion causes those molecules to move around and spread out it causes a condition of high entropy.
As an object cools the object molecules slow down so that the forces between molecules can organize them. At absolute zero all of the heat has removed and the molecules have stop moving. The forces between molecules now fully organize the molecules resulting in zero entropy.
Absolute Zero is the lowest limit possible on temperature is defined as 0 Kelvin which is -273.15 oC or -459.67 oF.
The lowest temperature actually reached was achieved by MIT researchers in 2003. That temperature is 45 nK which is 45 ten billionth of a oC above absolute zero.
In practical application, while absolute zero is the lowest limit on temperature it is not actually achievable. You can get infinitely close but not exactly at absolute zero. You just cant get rid of that last bit of heat.