Bleed is one of the most important concepts in printing to ensure a professional looking end product. It deals with how a project is printed and cut. Bleed expands the design beyond the designated printing area (i.e. your design is slightly larger than the intended print size).
If there is no bleed, your design or text may either be slightly cut off or may end up with a horrible looking thin, white edge all around.
Here is an example of a business card with and without bleed. Note where the cutting edge is on these cards.
Generally we need 3 mm bleed all around a projecct. The standard size of a business card is 50 x 90mm but your design should add 3mm bleed all around, so the design size must be 96×56 mm.
Need to know more about bleed?