What's the difference between KB and KiB?

I've always wondered what the big deal was between 1000 and 1024.  Some hard drive manufacturers and cloud providers stress they support one or the other but I never understood why.  It's just 24 bytes, right?  Well, it adds up and makes a big difference.  Here's a nice overview: http://blog.pulsedmedia.com/2015/09/kibibyte-kilobyte-the-divider-1024-and-1000/