|We're all Homo here|
|A Gradual Science|
|Plain Monkey Business|
The fossil record is the set of all fossils - and it just happens to chart the course of evolution through time. It is one of the most significant pieces of supporting evidence for the idea that evolution is a rational and real explanation for the origin of the diversity of species. In general, the term "fossil record" refers to all fossils that have been excavated, examined and characterized so far by thousands of hardworking scientists and paleontologists over the last few hundred years. The fossil record is used as evidence for many of things, including for common descent, for mass extinctions, for the Cambrian explosion and for the fact that the Earth is considerably older than 6000 years. Plus for flood geology.
At the same time, the fossil record is yet another thing which shows that creationist ideas are untenable. Creationists like to claim that there are no transitional fossils (fossils that fill the "gaps" between one species and another) in the fossil record. This is probably because if one was presented to them, they would point out that there are now two new gaps on either side of it for which no transitional forms exist. Either that, or they are convinced that the fossil record is a hoax. But to scientists working on real research, the fossil record is a vital piece of evidence to study.
Due to the relative rarity of fossil formation (with factors such as time, location and pure luck governing what we can find), and the natural destruction of rock that holds fossils, it is unlikely that the fossil record will ever be 100% complete and comprehensive. Creationists don't (or don't want to) understand this, and insist that the absence of a single fossil disproves evolution outright. Scientists and palaeontologists who do understand how fossilisation works note that we can derive a lot of information from what we do have rather than dwelling on the information that we don't have/haven't found yet.