When you execute something synchronously, you wait for it to finish before moving on to another task. When you execute something asynchronously, you can move on to another task before it finishes. That being said, in the context of computers this translates into executing a process or task on another "thread." A thread is a series of commands (a block of code) that exists as a unit of work. The operating system can manage multiple threads and assign a thread a piece ("slice") of processor time before switching to another thread to give it a turn to do some work. At its core (pardon the pun), a processor can simply execute a command, it has no concept of doing two things at one time. The operating system simulates this by allocating slices of time to different threads. Now, if you introduce multiple cores/processors into the mix, then things CAN actually happen at the same time. The operating system can allocate time to one thread on the first processor, then a...
![A NASA spacecraft has discovered evidence of an ancient crater lake on Mars that was fed by groundwater. The discovery further supports the theory that Mars has a wet underground environment, and will hopefully lead to a better understand of the Red Planet's early evolution.
Read more: http://1.usa.gov/WPWByR via @[54971236771:274:National Aeronautics and Space Administration - NASA]](https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-ash4/s480x480/394905_10151443286587518_1631326325_n.jpg)
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