The Internet has transformed every part of our lives and is now changing arguably the most important part - our love lives. Internet dating is now the second most common way that couples meet. But what is the best way to make the online search for love successful? What are the 'matchmaking' algorithms that the big companies use? Do they really deliver the goods, or is it just clever marketing and actually a giant con? And is there really any science involved? Dr Hannah Fry and Dr Xand Van Tulleken investigate.