Many many many different media sizes ?

Hi,

I’ve just choosen that wonderfull theme (see here how I’ve customized it : http://theatre-en-liberte.com/), but wandering why I’ve so many sizes when uploading a media.

To show an exemple with one file I’ve :
fond04-150×150.jpg
fond04-268×164.jpg
fond04-268×268.jpg
fond04-300×300.jpg
fond04-332×205.jpg
fond04-432×432.jpg
fond04-700×300.jpg
fond04-700×393.jpg
fond04-700×700.jpg
fond04-900×395.jpg

I’ve just sent 4 photos right now… it leads me to 44 files in my /wp-contents/uploads

-> Is it due to Pinboard or WordPress Core ?
-> How to limit that, I’m not sure all of them are useful…
-> Which one can I delete ?

Thanks a lot 🙂