Multiple weaves, fibers, and treatments make for options galore in high-tech rainwear fabrics . These magnified samples are all nylon or a nylon blend. These stiffer fabrics are wonderful for ponchos, sailing gear, and the traditional yellow slicker you wore to grade school. You can cut, stitch in place, and not have to worry about fraying. Fabrics laminated with a poly-urethane or Teflon membrane, like Gortex, come in varying degrees of waterproofness and breathability.
Heavier membranes are more waterproof but less breathable.
That is to say, it takes awhile for the breathability factor to kick in, and by the time it does, you're likely to have already arrived at your destination. In terms of water-repellency, fabrics with light coatings or untreated tightly woven fabrics are entirely adequate for regular street wear.