For much of my early ministry I carried a small notebook around in my pocket to write down and keep random bits of information I might need later. This would include (before cellphones!) phone numbers, addresses, to do lists, shopping lists, and various thoughts about upcoming lessons I might be working on. While I still have a few of these pocket notebooks around, I no longer use them.
Instead I now use my Samsung Galaxy Note 9 smart phone with the free Google Keep notes app on it. What a useful, versatile and handy app this is! Everything I enter in it immediately is available on the Google Keep app on my Apple iPad, in the Google Keep app in my laptop and desktop’s Chrome web browser, and even by going to the https://keep.google.com website and logging in using my Google Gmail account.
I use Keep mostly as a place to type in the various bits of info I want to keep, but it has many additional features I have not even tried. Read about some of the many things you can do with Google Keep at these websites: PCWorld, Lifewire, and PCMag.
There are numerous other apps available which do more or less the same thing as Google Keep – think Evernote, Apple Notes, etc. But I wholeheartedly recommend the free Keep app for its combination of ease of use, versatility, and almost universal accessibility on any device.