I would like to know if its mandatory to leave the file extensions on a file name when using a Mac runing OS X Mountain Lion. It's kind of a stupid question maybe but I'm kinda new to the Mac environment and I'm not really sure about how to handle this. Some files I created with MS Office for Mac have the ".docx" extension at the end of the name ("exemple.docx") but others don't have it, yet they open without problems. Can I erase the extension name or would I later have problems if I do so? Would this affect a file if transferred to a PC? Thanks in advance for your insight on this.