In printing, 'bleed' refers to extra printing that is done around the edge of a design and then trimmed off. Bleed is used in virtually all printing to compensate for small printing and cutting inconsistencies.
When you prepare your artwork, any designs or background colours should be extended to cover the bleed area. Important aspects of the design and text should not be extended into the bleed area as it will get trimmed off.
All of our stickers require 1mm of bleed all round, except for circular stickers which require 1.5mm all round. For example, Square M stickers are 98 x 98mm, but the artwork needs to be 100 x 100mm. After printing, the stickers are trimmed down to 98 x 98mm.