What is "resolution"? What resolution should my image / photo be for uploading?

Resolution is the degree of detail visible in a raster or vector image.

 

Raster images (like photos) are comprised of pixels - or, dots of color.

• High resolution means there are many dots per inch.
• Low resolution means fewer dots per inch, and poorer quality.
• For VistaPrint products, aim for at least 300 dpi at the desired image size unless the product indicates otherwise.

Vector images are not comprised of pixels; they're calculated and displayed with the help of mathematical equations.

• They can be stretched to any size while maintaining high quality.
• It is preferable to use vector images whenever possible.