If you are using macOS 10.13.4 and you are running 32-bit applicatis, you will see a new warning April 12 stating that you need to update them. Here's what it means, as well as how you can check the applicatis you still use 32-bit.
macOS 10.13.4 displays 32-bit applicati warnings  What are 32-bit and 64-bit applicatis?
64-bit applicatis can access more memory and potentially run faster than 32-bit applicatis. This assumes, of course, that your Mac has a 64-bit processor. Modern macOS technologies, such as metal graphics accelerati, are 64-bit features and will not work Macs equipped with 32-bit processors.
[ How to tell if your Mac is 32-bit or 64-bit ]
64-bit support started with macOS 10.5, and now 32-bit support is being removed. Apple has begun to require 64-bit support for all titles submitted to the Mac App Store in January
Why do I see a warning that apps are not optimized for my Mac?
Apple is trying to give everye as much warning as possible that eventually macOS will be 64 bits ly. If …