TeXShop is a TeX previewer for Mac OS X, written in Cocoa. Since pdf is a native file format on OS X, TeXShop uses "pdftex" and "pdflatex" rather than "tex" and "latex" to typeset in its default configuration; these programs in the standard TeX Live distribution of TeX produce pdf output instead of dvi output. TeXShop uses TeX Live, a standard distribution of Tex programs maintained by the TeX Users Group (TUG) for Mac OS X, Windows, Linux, and various other Unix machines. The distribution...