The reason I have choosen Jpeg to upload these final versions of the logo i have created is because on the internet jpeg is the best quality that can be sent around easily and still maintains some good quality other than some other formats. For a billboard i would use a vector file because you can stretch it and it wont pixelate at all so it is perfect for billboards. I would use jpeg for a letter head too because all the tests i print were on jpeg and they had extremely good quality.