Defination of dating
To understand radiometric dating techniques, you first have to have an understanding of what is being measured, how the measurement is being made and the theoretical as well as practical limitations of the system of measurement being used.As an analogy, say you find yourself wondering, "How warm (or cold) is it outside?
The method is also technically challenging because lead can "leak" out of many types of rocks, sometimes making the calculations difficult or impossible.
Say a second friend who is aware of this arrangement visits and notices that your carton of ice cream contains 70 raisins and 10 chocolate chips.
She declares, "I guess you went shopping about three days ago." How does she know this?
You also need to know when you can or cannot apply a particular type of device to the task at hand; for example, if you want to know how hot it is on the inside of an active wood stove, you probably understand that putting a household thermometer intended to measure body temperature inside the stove is not going to prove helpful.
Be aware also that for many centuries, most human "knowledge" of the age of rocks, formations such as the Grand Canyon, and everything else around you was predicated on the Genesis account of the Bible, which posits that the entire cosmos is perhaps 10,000 years old.
Calculations involving radioactive isotopes are more formal but follow the same basic principle: If you know the half-life of the radioactive element and can measure how much of each isotope is present, you can figure out the age of the fossil, rock or other entity it comes from.