* Raw material: Wood pulp (various types), cotton, bamboo, recycled fibers, etc. Each raw material leads to different paper properties.
* Manufacturing process: Different pulping methods, bleaching techniques, and finishing processes create a huge variety.
* Weight and thickness: Paper comes in a wide range of weights, from lightweight tissue to heavy card stock.
* Surface finish: Coated, uncoated, textured, embossed, etc.
* Color: Beyond the standard white, paper comes in a vast array of colors.
* Intended use: Printing paper, writing paper, drawing paper, tissue paper, packaging paper, etc. each with specialized properties.
* Special treatments: Water resistant, fire resistant, etc.
Because of these many variables, there are thousands, if not tens of thousands, of different types of paper available commercially, and countless more variations possible. It's simply impossible to give a precise number.