So far, we've been talking about the abstract idea of a projection. Let's dive into OpenLayer's Projection class, OpenLayers.Projection, which is what we use to actually handle projections. The Projection class relies on an external library called Proj4js, which can be found at http://proj4js.org. First, we'll talk about what we can do without the proj4js library, and then talk about what we can do with it.

my_proj = new OpenLayers.Projection('EPSG:4326', {});