There are two types of Chalk that can be used for calligraphy and lettering.  Traditional school chalk that looks authentic and can be rubbed off easily or a water based/oil based chalk pen which has a more painted look.  The oil based pen is great for a more permanent project.  They can both be used to write calligraphy or lettering on black boards, white boards, restaurant signs, wedding signs, windows and a variety of different materials.