Your daily tip for today will help you understand what happens internally in the computer system when a reboot is initiated. There are two kinds of reboot, Soft Boot and Hard Boot (Cold Boot).
A hard boot occurs when the computers electrical power is cycled (turned on and off). Occasionally a cold boot occurs when you turn the computer off for the day, and turn it on again. It can also occur when there is a power failure, a fatal computer error (where the restart signal to the processer is not functional) or even by accident. If a system is put into hard boot in a way that should not happen (ie, a power failure), it leaves the hard drive in a "unclean" state. This is a major cause of data corruption, and hard drive failure. A cold reboot performs a P.O.S.T (Power On Startup Test). This test usually runs the bios to load any drivers, and adapters needed for the operating system. A cold boot also resets all of the adapters which communicate with your ports. A cold boot is the only way to accomplish this task and relieve it of any cached data (if it has the functionality). When a computer is shutdown, it also discharges any capacitors on the motherboard (some systems may take upto 10 seconds). Additionally it also gives the hard drive time to completly stop spinning and reset the cursor.
A soft boot is, well, the complete opposite. It is usually initiated by a software installation, a software upgrade, or even a non-fatal error in Windows/Linux. A soft reboot does not cut of the power to the computer system, and thus leaves the computer in a state where startup times can be faster by skipping the P.O.S.T. A soft boot often fails to reset the power to all adapters. It does not discharge the capacitors on the motherboard, and does not stop the hard drive. A soft boot assumes that the POST was successfull, and all hardware is functional and running upto speed.
If your computer system has low memory, or you find that it has slowed down over the duration of three, four days (or however long it has been on), you may find that a soft reboot may increase speed significantly. I would recommend shutting down your PC to make it last longer.