Simply counting the number of rings will give one a fairly good idea of the age of the tree.
Since the dawn of the space age in the 1950s and the discovery of extrasolar planets in the 1990s, the model has been both challenged and refined to account for new observations.
This challenge is mainly headed by Creationism which teaches a young-earth (YE) theory.
A young earth is considered to be typically just 6,000 years old since this fits the creation account and some dating deductions from Genesis.
Trees undergo spurts in growth in the spring and summer months while becoming somewhat dormant in the fall and winter months.
When a tree is cut down, these periods are exhibited in a cross section of the trunk in the form of rings.