Researchers need big computers to testify models, make predictions... But very few projects can afford supercomputers. BOINC is the acronym of Berkeley Open Infrastructure for Network Computing. With BOINC you can share a part of your computer to help some science projects that needs long computations. In that way you can help researcher to find new drugs, exploit the data of the LHC or detect new stars... That's why they need your help !
It is very rare that our computer is running at maximum when we are on it. This is a screenshot of my computer when I'm not running BOINC. My CPU use only 40% of it capacity because it has nothing to do. BOINC does is fill that void with calculations that make sense.
If you have a good computer (or several) and you might want to help scientific research without taking your time, this is the perfect deal. If you have more time, there is a forum for each project or you can discuss aspects of the project. In some scientific problems, GPU are faster than CPU. That's why PC for Gamers are really appreciated in BOINC because they have good GPU in it.
After using BOINC you will see your CPU use to climb until 100% or whatever you set the threshold. Do not worry about your PC. A CPU is made to do calculation. This is not a problem if it's used at 100%.
BOINC does its job in the background. You can still use your computer as you want. You can also edit your preferences as desired. Choose the projects you want to participate. For example, calculating when the computer is not used, do not calculate when the computer is on batteries... Set your preference as you wish, BOINC should not interrupt your normal use of the computer.
That's all folks !
Next time I will speak about Gridcoin : a good way to be rewarded for this work !
Feel free to 
:D
Great post, tag #gridcoin! :D
Fixed !
I put the banner also ! ;)
#curecoin is for Folding and Gridcoin is for BOINCing.
Two scientific research coins. :)