iphoto iphone library photo

As I just bought +icloud for me and my family I need to be sure if I backup my photo library to icloud does the photos and videos dowloaded and backup-d will stay there if I delete them in my iphone photo library to get more data space on phone.

I could not find topic related to this quarry so sending here.

Hope that me using icloude to save data ones backed up stays there even if deleted on iphone and that only way to delete anything on icloude I should connect to it and administer there unwanted files.

Reg

Kristian