I believe with exceptionally high degrees of confidence that the sun will rise tomorrow. I have this belief because the sun has been observed to rise every day for something like a few million times in a row and I've never once witnessed it not rise. This belief is so strong I could comfortably call myself certain of it, but it's still nevertheless a belief. For most practical purposes, 'certainty' means an exceptionally high degree of confidence, where the margin for doubt becomes too small to bother ourselves with. But true certainty seems like something that can only arise from pure mathematics, not through observations of the world. I am truly certain that triangles have three sides, whereas I am 'merely' exceptionally confident that gravity exists.