This tag is for questions relating to "tail-distribution" which essentially means how much probability is distributed over the largest values(usually) of the random variable.
The tail behavior of a probability distribution is known to be closely related to the behavior of the characteristic function of the distribution in the neighborhood of the origin.
A distribution may be viewed as A fat-tailed distribution is a probability distribution that exhibits a large skewness or kurtosis, relative to that of either a normal distribution or an exponential distribution. In common usage, the terms fat-tailed and heavy-tailed are sometimes synonymous; fat-tailed is sometimes also defined as a subset of heavy-tailed. - if it assigns smaller probabilities for larger values of the variable, or heavy tailed - if it assigns larger probabilities for larger values of the variable.
Again a fat-tailed distribution is a probability distribution that exhibits a large skewness or kurtosis, relative to that of either a normal distribution or an exponential distribution. In common usage, the terms fat-tailed and heavy-tailed are sometimes synonymous; fat-tailed is sometimes also defined as a subset of heavy-tailed.
For more about this you can see the following (also the references therein):
https://en.wikipedia.org/wiki/Heavy-tailed_distribution
