You've put in all that hard work to create the photograph you wanted, so don't undo a lot of your efforts by not properly resizing for which ever platform you're going to post it on, including your own portfolio.
Resizing your photographs is one of those tasks that's so simple and easy at first glance, you might not think about the process. Furthermore, most platforms like Instagram and Facebook will just resize the images for you, so why bother? Well, as almost every photographer I've ever spoken to has noticed with platforms like Facebook, the quality loss is substantial. On platforms that don't automate the process, you could end up making your website incredibly slow to load for many viewers.
In this video Karl Taylor shows you how to properly resize images for web and social media, including your portfolio which is by far the most important of the lot. Taylor does a brilliant and clear job of explaining many important factors, so I won't do him a disservice by repeating anything. One tip I would give is that for certain applications of your images — for example, setting an image as your Facebook page's banner — there are native dimensions which you ought to aim at matching. As of the day I'm writing this article, the Facebook banner size is 820 x 462 pixels.
How do you resize your images?