20. Answers.com -- 49mm users in the U.S. in December 2012

19. Walmart.com -- 49mm

18. Go.com -- 49mm

17. Microsoft.com -- 52mm

16. Apple.com -- 53mm

15. CNN.com -- 53mm

14. Live.com -- 56mm

13. eHow.com -- 57mm

12. About.com -- 62mm

11. Ask.com -- 63mm

10. eBay.com -- 64mm

9. Blogger.com -- 67mm

8. Bing.com -- 75mm

7. Wikipedia.org -- 86mm

6. MSN.com -- 100mm

5. Amazon.com -- 105mm

4. YouTube.com -- 128mm

3. Facebook.com -- 150mm

2. Yahoo.com -- 171mm

1. Google.com -- 191mm

Top 20 Websites in the World according to comScore:

20. Amazon -- 163mm users worldwide in December 2012

19. Sina -- 169mm

18. WordPress -- 171mm

17. Apple -- 172mm

16. Sohu -- 176mm

15. Bing -- 184mm

14. Twitter -- 190mm

13. Taobao -- 207mm

12. Ask -- 218mm

11. Blogger -- 230mm

10. MSN -- 254mm

9. Baidu -- 269mm

8. Microsoft -- 272mm

7. QQ -- 284mm

6. Live -- 390mm

5. Wikipedia -- 470mm

4. Yahoo -- 470mm

3. YouTube -- 722mm

2. Google -- 783mm

1. Facebook -- 837mm