does reducing pic size reduce quality?

[Matt]

Yes, reducing size reduces quality, but a 20mb file has much more information that can be displayed on a monitor anyway. If all you are doing is sharing through social media, you can reduce the image to 1200 pixels on the wide side and that is plenty for almost any monitor. Go to 2,000 pixels if you want. For an 8x10, that is is only 5 MP, and a jpeg at that. Save at a medium-high quality and you should not be more than a few 100 kb.

Of course, you can't go back and print this file without losing quality, so make sure you keep the higher resolution files as well.