To create bitcoins (mine bitcoins), the virtual currency that is getting so much attention lately, exceeding a thousand dollars per unit, we can use some programs that use the power of our computer to solve mathematical problems. The more problems they can solve, the more bitcoins they will generate, something for which a huge structure is necessary.
To get an idea of the magnitude of this structure, look at what a Hong Kong company has set up to be able to mine Bitcois, hundreds of computers connected with a single objective: to solve the problems that generate such a tasty currency. A traditional computer, however powerful it may be, cannot generate a sufficient number of coins to compensate for the cost of electricity by having it turned on (you can check it on this calculator), so it is always necessary to have several computers working in parallel to obtain interesting results.
With that in mind, it is not uncommon for malicious programs to start appearing on computers to start instead of displaying ads left and right (adware) are responsible for stealing CPU resources and sending the results to a center where they will be analyzed in order to generate the desired bitcoins.
This has been confirmed in malwarebytes.org, where they show new processes that can consume up to 50% of resources, such as jh1d.exe, corresponding to the popular jhProtominer, sometimes hidden behind free online proxy programs, for example, as demonstrated in that article (YourFreeProxy, in this case).