Carbon 14 dating is used for "dating" organic sample.
The theory is that cosmic rays reacts with upper atmospheric nitrogen to form Carbon14. The Carbon 14 falls to Earth gets absorbed by plants and animals so that the Carbon 14 levels constant through an animal's life and Carbon 14 levels drop from decay after death. The date is based on Carbon 12 / Carbon14 ratio.
Like all dating methods there are assumptions.
Carbon 14 has a half life of 5,750 years, theoretically giving it a maximum datable age of about 100,000 years. Now Carbon 14 dates this high be reconciled with Biblical dates?

The answer is that there was rapid post Flood increase in Carbon 14. This could have resulted from post flood fluctuation in Earth's magnetic field. The Solar system could have been exposed to above normal cosmic ray influx this would be consistent with accelerated nuclear decay during the Flood. It would also explain cosmic ray dating of meteors. These are not mutually exclusive.
This theory makes 3 testable predictions.
Anomalous C-14 Dates Associated with
Various Post Flood (Ice Age) Fossils
Animal C14 age
in yearsItem C14 age
in yearsItem Union Pacific Mammoth 11,300 Most recently
formed ivory5,000 Wood in surrounding
gravelChekurovka Mammoth 26,000 Hair 5,610 Overlaying peat Ferguson Farm Mastodon 8,800 Bone collagen 6,200 Mud with organic matter
with in the skull cavitiesFairbanks Creek Musk Ox 24,000 Scalp muscle
tissue17,200 Hair
Animals that have been found with significantly different Carbon 14 dates in different parts of their bodies or surrounding organic material, fulfilling prediction #1.

This shows definite and constant inconsistency between old Carbon 14 dates, when applied to tree rings and other uniformitarian methods. Carbon 14 give a fairly accurate date up to about 2,500 years ago, the it start deviating significantly younger than tree rings. There is some circular reasoning since older tree ring dates are often matched by uses of Carbon 14 as dealt with in the article on Tree Rings. While the carbon 14 does give a younger age the other methods, it only shows that they build up faster than Carbon 14 did.

It gets worse when it is compared to other methods. While there is a general trend there is no real constancy. This full fills prediction number #2.
Organic material found in rocks supposedly too old for C14 dating has shown measurable amounts of C14.
Unreliability of Radiometric Dating and Old Age of the Earth.
This full fills prediction #3.
So all three predictions of a rapid post Flood increase in Carbon 14 seem to have been confirmed, this strongly indicates that this theory is correct.

This model is further supported by the fact that Carbon 14 is found throughout the geologic column and the amounts do not vary with the location in the column above the Precambrian. This suggests that the layers formed quickly and at the about the same time. It further shows that the fossil organisms found in these rocks lived at the same time.

The only trends are as follows:
In rocks alleged too be to old to have remaining C14
Dated < 600 Mya. average a C14 level of 0.292 pMC.
Dated > 600 Mya. average a C14 level of 0.062 pMC.
Recent objects show general lowering of C14 with age.
This is 100% consistent with a Young Earth creation model and the basic trend predicted by Young Earth creation.
MEASURABLE 14C IN FOSSILIZED ORGANIC MATERIALS:
CONFIRMING THE YOUNG EARTH CREATION-FLOOD MODEL