Relative dating is used commonly when looking at the relative order of geological events.What can complicate relative dating is when the strata is not the right way up!For example, techniques based on isotopes with half lives in the thousands of years, such as Carbon-14, cannot be used to date materials that have ages on the order of billions of years, as the detectable amounts of the radioactive atoms and their decayed daughter isotopes will be too small to measure within the uncertainty of the instruments.One of the most widely used and well-known absolute dating techniques is carbon-14 (or radiocarbon) dating, which is used to date organic remains.In historical geology, the primary methods of absolute dating involve using the radioactive decay of elements trapped in rocks or minerals, including isotope systems from very young (radiocarbon dating with Radiometric dating is based on the known and constant rate of decay of radioactive isotopes into their radiogenic daughter isotopes.Particular isotopes are suitable for different applications due to the type of atoms present in the mineral or other material and its approximate age.Relative dating is useful during field work to measure, for instance, the throw of a fault, or to re-instate the missing part of a stratigraphic sequence.In micro paleontological analysis, you may not need the general view if all you are trying to establish is which of two foraminifera is the older.
Over time, the accumulated deposits compress and harden.
Absolute dating is the process of determining an age on a specified chronology in archaeology and geology.
Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy.
An absolute age is one determined usually by mass-spectrometry where an isotope is measured and then an age can be calculated (a very very basic explanation).
So in the end you can say this fossil is 50 thousand years old (always with an associated uncertainty).