Grammage are the same weight paper having different cut size. However, a sheet of common copy paper that has a basis weight of does not have the same mass as the same size sheet of coarse paper (newsprint). In the former case, the standard ream is 500 sheets of paper, and in the latter, 500 sheets of paper. Here are some basic ream sizes for various types of paper. Units are inches except where noted. Sheets can be cut into four sheets, a standard for business stationery known conventionally as "letter sized paper". So, the ream became commonly used. The book-paper
Inkjet paper include coatings engineered to receive and hold ink. Fine art papers are usually made of rag pulp (100% cotton being the most common) but may also be have an alpha-cellulose base. Some descriptions and comparisons of fine art inkjet papers are here, here, here, and here. Some fine art papers are mold made, while others are machine made, and may vary considerably in surface texture. Many fine art papers are available in pre-cut sheets or in rolls. Standard office paper has traditionally been designed for use with typewriters and copy machines, where the paper usually does not get wet. With