please explain carbon dating method of fossils?

Radiocarbon datingis a method of determining the age of an object by using the properties ofradiocarbon(¹⁴C), a radioactiveisotopeof carbon. The method was invented byWillard Libbyin the late 1940s and soon became a standard tool for archaeologists. It depends on the fact that radiocarbon is constantly being created in the atmosphere by the interaction ofcosmic rayswith atmospheric nitrogen. The resulting radiocarbon combines with atmospheric oxygen to form radioactivecarbon dioxide. This is then incorporated into plants byphotosynthesis, and animals acquire¹⁴Cby eating the plants. When the animal or plant dies, it stops exchanging carbon with its environment, and from that point the amount of¹⁴Cit contains begins to reduce as the¹⁴Cundergoesradioactive decay. Measuring the amount of¹⁴Cin a sample from a dead plant or animal such as piece of old wood or a fragment of bone provides information that can be used to calculate when the animal or plant died. The oldest dates that can be reliably measured by radiocarbon dating are around 50,000 years ago, though special preparation methods occasionally permit dating of older samples.
The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained. Research has been going on since the 1960s to determine what the proportion of¹⁴Cin the atmosphere has been over the past fifty thousand years. The resulting data, in the form of a calibration curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age. Other corrections must be made to account for different proportions of¹⁴Cin different types of organism (fractionation) and different¹⁴Clevels in different parts of thebiosphere(reservoir effects).
Measurement of radiocarbon was originally done by beta-counting devices, which counted the amount ofbeta radiationemitted by decaying¹⁴Catoms in a sample. More recently,accelerator mass spectrometryhas become the method of choice; it can be used with much smaller samples (as small as individual plant seeds), and gives results much more quickly.