Even today, fitness trackers have a few advantages over smartwatches: they're easier to wear since they have slimmer, lighter profiles. They're less complicated because they're designed primarily to keep you fit (not necessarily for things like emailing on the go). And, perhaps the most important distinction of all, fitness trackers are generally less expensive than smartwatches.
Wirecutter writers have been researching, testing, and writing about smartwatches since early 2013, just after the first Pebble watches were shipped to Kickstarter backers. I’ve personally worn nearly every notable smartwatch since that first Pebble and have written about them for a number of publications, including IT World and Fast Company. I also have extensive experience with Android phones, having written the (since outdated) Complete Android Guide and numerous articles about Android. I also contribute to and help edit the Wirecutter guide to the best smartwatch for iPhones.