What is a Bleed?
A bleed is a term in printing that is used to describe a document on which the images touch the edge of the page. When a document has a bleed, it must be printed on a larger sheet of paper and design extended outwards of atleast 1/8th of an inch. By doing this we avoid any white spaces on the edge of the document due to the image shifting while being printed and trimmed.
Any objects in your artwork that touch the edges of the document require bleed, for instance a background colour or image should spread to cover the entire bleed area as should any objects that creep in from the side of the page. The bleed area is just excess image that gets printed, but it gets trimmed off.
What is The safe Area?
The safe area is where all your important elements like text should go. No important elements should go outside the safe area.
What are Crop Marks?
Crop marks, also known as trim marks are small lines approximately 0.5 inches long that shows the actual document size and where the document needs to be trimmed.