"fan" on the computer start regularly On my MBP (13-inch, Mid 2012), I note that the "fan" starts regularly for very little. Could anyone be able to tell me why is it the case and what can I do to fix it?

I know if the fan starts it is because the temperature is to height, but I don't know what to do to decrease the temperature when I work on my computer.







That last picture comes from the SMCfanControl application. Is it normal?
Open Activity Monitor and check the "Energy" tab. Click on "Energy Impact" to see what is using the most energy. This is likely what is causing the heat. Close this program when not in use. You can monitor the temp with Temperature Monitor (built into OS X). Spotlight > Temperature Monitor  

Also, this 3rd party program can help, SMCfanControl: https://www.eidac.de