Type 1 fonts, the kind that came with Macs in the 1990s, will no longer be supported by Adobe software. Unless you've been around a long while, chances are this won't affect you. But designers of vintage may soon have to set themselves up one of those single-purpose corner computers that no-one else is allowed to mess with. Christopher Slye:
Type 1, the venerable font format, was once the linchpin of desktop publishing, but decades ago the demands of technology and global design made the OpenType font format necessary. If you think this might affect you, the easiest place to start is by looking at your fonts. If you have font files without a suffix of either ".otf" or ".ttf," then they're probably the Type 1 format. Apple's macOS will identify them as a "PostScript Type 1 outline font," and on Microsoft Windows you'll see a file with a ".pfb" suffix (possibly with a ".pfm" companion file). You can also look at the icon next to the name in an Adobe application's font menu. If your fonts aren't handy, but you suspect they might turn up later, just think about the timeline: Fonts or documents you were using before (roughly) the turn of the century are from the pre-OpenType era.