OS X applications are usually distributed as disk images (.dmg) containing the app itself, a symlink to /Applications for easily copying the app there, and mayb

OS X applications are usually distributed as disk images (.dmg) containing the app itself, a symlink to /Applications for easily copying the app there, and maybe supporting files. Installers are unusual, except for huge software packages like Office or odd things like preference panes, which are not as easy to get to the right place. I presume that people using Macs tend to be 1) wary of downloading any programs from random websites and 2) wary of having to run something like an installer. The Mac App Store means that people will only do these things less going forward.