Apple usually updates their operating systems annually for iPhones and iPads, at the same time or near to the same time as they update their MacBooks and iMacs. With the advent of a range of new products like the Watch, Apple TV and HomePod, for the avid Apple user it sometimes it feels like every week there is a new update to contend with. In reality, the main kernel of the all the varied systems are only changed every twelve months and this year the move from macOS 10.14 (Mojave) to macOS 10.15 (Catalina) is a game changer for macOS driven systems.
The name of the new OS comes from Santa Catalina which is a beautiful island off the hectic coastal city of Los Angeles in California and true to the area, it is a very special tourist location. The OS is a bit special too!
As far as the software version of Catalina is concerned, everything that ran on Mojave should run on Catalina provided it is built on the latest 64bit code. This means that whereas Mojave was tolerant of applications written using 32bit code, Catalina will have none of them so this means that you might find some of your old beloved apps won’t run on the new OS and you’ll have to find a replacement app. Apple has played very fair with its customers on this one as there have been many warnings of the impending change for some years so it really shouldn’t come as a surprise. Invisibly to most users, the majority of developers moved all their applications they want to support to 64bit code years ago so you shouldn’t meet too many problems but you have been warned to look before you upgrade!
The really good news is that any Mac-based hardware, such as MacBook, MacBook Pro, iMac, Mac mini or even the MacPro powerhouse, will run Catalina provided the hardware was built in 2012 or later and is capable of running the Metal graphics protocols that came in that year. This is a really outstanding policy of longevity that other computer manufacturers should try to emulate especially in this throw-away society.
If you want to dig deeper, may I recommend the Apple Insider review below which tells you about the applications that have changed and the extra functionality Catalina brings - just copy this into your web browser address line -
https://appleinsider.com/articles/19/10/07/review-macos-catalina-1015-is-what-apple-promised-the-mac-could-be-and-is-a-crucial-upgrade
This covers much more than I could but be aware, it is long and detailed and will require at least three cups of coffee and maybe even a cream bun to get through it!