Letterhead is an integral part of every company. In most cases, the letterhead with information about the company is the first medium that the company's partners, as well as employees and customers, encounter. The most common letterhead format is A4, but A5, A6 or A3 formats are also often used. A typical weight for letterhead is 90 g/m2 or 115 g/m2 on offset or chalk paper.