One of my little secrets for keeping track of Mac product information, from the original 1984 Macintosh 128K to the present models, is an app called Mactracker. Mactracker is a database of all Apple products, from 1984 on. Mactracker doesn't just cover the Mac; the database also includes accessories, such as mice, keyboard, cameras, and printers, as well as non-Mac items, such as iPods, iPhones, and iPads.
If I need to know which system shipped with a specific Mac, or how much memory a Mac model can hold, Mactracker is my go-to app to get this information.
You can also use Mactracker to track the history of your personal Macs, letting you know when a Mac is in warranty, nearing the end, or out of warranty.
Mactracker has more capabilities than I can outline here. I highly recommend adding it to your toolbox.
Mactracker is free; donations are accepted.
See other software choices from Tom's Mac Software Picks.