For many people, Google Photos, Flickr, and other cloud-based image hosting services are perfect for backing up photos, sharing them, and organising them into galleries. If you'd rather use a self-hosted solution you control, or maybe use one in addition to those cloud services, Chevereto is worth a look.
Chevereto has been around for a long time -- it's not new, really, but what's interesting about it is that the developer offers both a paid, hosted service you can sign up for on their homepage, but also Chevereto Free, an open source version of the gallery software you can download from Github (linked below) and install and run on your own web host. Best of all, they offer an installer you can run from the web, or even installation services so you can make sure your gallery is locked up tight and installed properly.
Chevereto itself is a richly featured gallery tool. You get beautiful, responsive galleries that look just as good on mobile as they do on the desktop, profiles for multiple users, an image uploader so you don't have to do things in small batches, social features for easy image sharing (and for easy login), and feature updates as they're available. The whole service is worth a look if you'd rather take control of your own photo library, but don't know where to start. There's a paid version of the self-hosted solution as well that comes with support and a few more features, so check that out too, if you're interested in supporting the project.