"Parts" describes the number of copies plus the original that make up the complete document (i.e. 3-part check = 1 original plus 2 copies). Manual and continuous checks/forms use carbonless copies. Laser checks/forms use a separate sheet for each part.
Order the number of copies required for your accounting records, as well as those distributed to employees, clients or vendors. Copies are color-coded for easier use.
2-part: (original + one copy)
3-part: (original + two copies)
4-part: (original + three copies)