Nowadays the term cartridge paper is used to denote a better quality paper than the normal machine-made office paper. The structure of the paper feels, and is, stronger, and the grain is less pronounced. Cartridge paper might be described as half way between office paper and hand made paper. It is favoured over office papers for the manufacture of journals and quality hand-made items. Bookbinders go to a lot of trouble making their books ~ they prefer not going to spoil the results by using office papers of lesser quality.
There is more information on cartridge papers here.
The surface is slightly rougher than office papers, and usually takes pencil, crayon, pastels and even acrylics and watercolours well. Spirit based markers may show through the lighter grades, but the paper usually has no significant show-through.
It is normally made in white or slightly off-white (ivory) or “natural” (cream). It is very difficult to describe the colours sensibly over the WWW. If the tint is critical then please shop for this item on the High Street where you can see the colour, feel the crackle, and maybe even test the surface with your chosen media. Or buy our mixed pack of sheets.