**Sample-Path Analysis of the Age of Information (AoI) and Its Applications to FCFS Single-Server Queues**

The age of information (AoI) is a metric for the freshness of information, which is defined as the time difference between the current time and the time-stamp of the information. Analysis of the AoI has been attracting a considerable attention in recent years, because of its wide applicability to systems where the freshness of information is the primary concern. In this talk, a general formula for the probability distribution of the AoI is derived through a sample-path analysis. Applications of this formula to FCFS GI/GI/1, M/GI/1, and GI/M/1 queues are also presented.