Prince of Spires
Istar
Since you're asking the question, I'm assuming you're self-publishing. Which means you'll likely either go with Amazon or Ingram Spark. The best thing to do then is to check out Amazon's guidelines for the cover => Paperback Submission Guidelines
I'm sure Ingram has the same, but I've never used them. As for Amazon, you will want
file size smaller than 650MB
300 DPI minimum. Advice is not to go above 600DPI, since then the file can become too big and take too long to process
cover must be pdf file
There are a few others, but those are the big ones for you. Ideally you want your pdf with CMYK since that gives the best colors, but RBG works.
I'm sure Ingram has the same, but I've never used them. As for Amazon, you will want
file size smaller than 650MB
300 DPI minimum. Advice is not to go above 600DPI, since then the file can become too big and take too long to process
cover must be pdf file
There are a few others, but those are the big ones for you. Ideally you want your pdf with CMYK since that gives the best colors, but RBG works.