Homogenization is used on fresh milk to prevent the separation of a cream layer. In more technical terms 'Homogenization is a fluid mechanical process that involves the subdivision of particles or droplets into micron sizes to create a stable dispersion or emulsion for further processing'. This external page here talks in detail about this technology....reading might be somewhat difficult but will do the job...also move around the site to read more if it intersts you ...
Homogenization forces hot milk, under high pressure, through small nozzles. The fat globules become small enough so that they remain evenly dispersed throughout the milk.
See: Pasteurization