h5ai is a "modern web server index." What's that, you may ask? Basically, it's a simple software that prettifies the default interface the Apache web server uses to list files in a directory. This may not sound like much, but if you want to publish files on the web using Apache (or any other supported web server, for that matter), this unassuming tool can make the whole experience of browsing and downloading files more pleasant -- which is a positively good thing.
So, you just got back from a trip, and you have tons of photos you want to share with the world. While there are dozens of photo sharing services to choose from, uploading megabytes of photos doesn't sound like a fun pastime. And why bother with a third-party service if you already have a Linux-based server? In this case, consider using Bizou.