Think of a thread as a process running within a process. By process i mean 'application' eg AH2, Word, or Firefox etc. So a process can have many worker 'threads' all doing different things, apparently, simultaneously.
A good example would be say outlook express: outlook express is the process, and it has a thread to respond to user input (mouse, keys etc), and spawns other threads to check your mailbox 'in the background'. It does this so that when it checks for mail it doesnt block the responsiveness of the actaul application (eg stop responding to mouse clicks etc cause it is busy checking your mail). Its doing several things at once to make the user experience 'nicer'.
In fact most applications now days are multi-threaded (in a windows/GUI world) and can have as many threads to do as many seperate tasks it needs to do simultaneously without stopping the others.
To cloud the picture further, all this talk of simultaneous processing is actually a lie. Most PCs have a single processor (times are now changing) which has/is a single 'core'. A processor can only execute instructions in sequence (eg one after the other). There is no such thing as two processes or threads running at the same time. What actually happens is the operating system (windows) round-robins all of the 'running' applications and gives them a small slice of time on the processor while the others wait their turn. Then it stops that process and puts it to sleep and then gets the next out of the queue and gives that a turn. So on, and so on. It all happens so fast it gives us the illusion of many processes running simultaneously.
So, now with the advent of multi-core and multi-processor PCs becoming commonplace, their now exists the opportunity for REAL simultaneous processing - eg one processor services one process, another another, etc etc up to as as many processors/cores you have.
Still with me? Good. Now the problem with true simultaneous execution is where two or more cores are competing over a shared resource (like a monitor, or memory, or disk etc). If the operating system doesnt enforce strict rules on how, who, and when resources can be accessed you can end up in a real sticky mess - to give a very simple explanation.
As for AH2 and its threading etc etc, i have no idea... Im sure HTC could fill in those details.
