Mac fan runs loud

my macbook white runs very loud the fan just basically is so loud when i run youtube to watch something or any kind of movies online can you suggest why does it happen im kinda worried mac gets very hot
thank u

If your Mac gets hot, that is why the fan is running. It is indicative of a problem with heat.

Give us more info on the macbook.

i have 2007 macbook white it gets hot when i watch news video youtube etc i dont run various apps at once mostly its the video than the fan kicks in and makes mac really hot u think i need new fan? help please

YouTube videos and flash content taxes (puts a heavy load on) the CPU of the machine. The fan ramps up RPM to cool it down. If it didn't do that, the machine would shut down otherwise the CPU could be destroyed.

It's the increase in the RPM that makes the loud noise. It's normal. Just make sure your machine is on a flat surface to allow cooling under and around it.