As the boundaries between PR and advertising become ever more undefined we thought this list of the most shared ads of 2013 would be interesting to see. But what is it that makes them so shareable?

The ‘Dove Real Beauty Sketch’ ad has topped the 20 most shared ads of 2013 according to Unruly.

The ad has had 4.24 million shares across Facebook, Twitter, and the blogosphere since its launch in April.

Here is a list of the top 20 for you to enjoy:

1. Dove 'Real Beauty Sketch'

2. GEICO 'Hump Day'

3. Evian 'Baby and Me'

4. Kmart 'Ship my Pants'

5. Cornetto 'Yalin'

6. Budweiser 'Brotherhood'
7. Pepsi Max 'Test Drive'
8. MGM/Carrie 'Telekinetic Coffee Shop Surprise'
9. Ram Trucks (Chrysler) 'Farmer'
10. Volvo 'The epic split feat. Van Damme'
11. Neft Vodka 'Biting Elbows'
12. True Moves 'Giving'  
13. PooPourri 'Girls don't poop'
14. GoPro 'Fireman saves Kitten'
15. Phonebloks 'Phonebloks'
16. Three 'The Pony' #DancePonyDance
17. H&M 'David Beckham'
18. Rockstar 'Grand Theft Auto V gameplay'
19. Sony 'Used Game Instructional Video'
20. Code.org 'What most schools don't teach'