Troubleshooting is a systematic approach to problem solving that is often used to find and correct issues with complex machines, electronics, computers and software system.
It enables the repair and restoration of a computer or software when it becomes faulty, unresponsive or acts in an abnormal way.
There are many answers to this question. The first step is normally a reboot, second, I would check witch task or service is taking up all the CPU cycles and check the system and error logs. The list goes on... I'm not sure how detailed you want to get.
It is a small external flash drive that can be used with any computer that has a USB port. These tend to be smaller than external hard drives or other means of storages.
