A4 letterhead paper refers to A4-sized, gridded writing paper.
The size of A4 letterhead paper is 21cm × 29.7cm. This kind of paper is often used for writing letters, practicing calligraphy, etc. It can have squares, horizontal lines, or no pattern. There are also many types of materials for A4 letterhead paper, including pure wood pulp paper, straw pulp paper and recycled paper.