References

The Periodic Table, first created by Dmitri Mendeleev, organizes all of the known elements in an informative array.

BUYING GUIDE These are the best running watches in every category, from Garmin Fenix 7 to Apple Watch Series 8 and Coros Pace 2.

Buying Guide Looking to check out macOS? Here are the best MacBooks for students you can buy right now.

BUYING GUIDE The best cameras for wildlife photography have impeccably accurate autofocus, a fast burst rate and sharp, detailed images — we've rounded up the best models.

BUYING GUIDE The best astrophotography cameras require excellent low-light capabilities — check out our favorite models to watch for this Black Friday.

These are the best Garmin watches you can buy in every category, from Fenix 7 and Forerunner 265 to Venu 2 Plus.

These are the best budget fitness trackers you can buy in every category, from Fitbit Inspire 3 and Garmin Vivosmart 5 to Amazfit Bip 3 Pro.

Buying Guide These are the best fitness trackers you can buy in every category, from Apple Watch Series 8 and Garmin Fenix 7 to Amazfit Balance.

BUYING GUIDE These are the best treadmills you can buy in every category, from NordicTrack x22i and Mobvoi Home Treadmill to Peloton Tread.

Buying Guide These are the best rowing machines you can buy in every category, from Concept2 RowErg and Ergatta Rower to Hydrow Wave.

Buying Guide These are the best electric toothbrushes for kids, from Oral B Kids and Philips Sonicare for Kids to AutoBrush Sonic Pro.

Buying Guide These are the best electric toothbrushes you can buy in every category, from Oral-B Genius X and Bitvae R2 to Waterpik Complete Care 9.0.

Volatile organic compounds (VOCs) are gaseous chemicals that are emitted by various household items, as well as natural sources.

REFERENCE Wondering how to improve the air quality in your home? This is what the experts have to say.

BUYING GUIDE These are the best dehumidifiers you can buy in every category, from Honeywell TP50WK to LG Puricare.

These are the best walking treadmills you can buy in every category, from Mobvoi Home Treadmill to Bluefin Fitness Task 2.0 Treadmill.

BUYING GUIDE These are the best air purifiers for allergies you can buy in every category, from Levoit Core 600S and GermGuardian AC4825E to RabbitAir A3.

BUYING GUIDE These are the best air purifiers you can buy in every category, from Levoit Core 600S and BlueAir Blue Pure 411i Max to Dyson Purifier Cool.

Buying Guide These are the best humidifiers you can buy in every category, from Dyson AM10 and Levoit LV600HH to HoMedics TotalComfort Deluxe.

Pangaea is Earth's most recent supercontinent, which existed 320 million to 195 million years ago.