So, why was I seeing all these relevant adverts? That's big data and digital advertising at play. Today, Google will know that your wife is pregnant by the internet searches she makes and Facebook will know whether your searching for a bigger house all based on the data you input in a site you visited or a post/status update made.
A few weeks ago, my wife asked me to do a Google search for a fruit juice-making machine. When I started my search, I clicked on the first link which took me to a Chinese vendor website selling industrial juice-making machines and subsequently I hopped from site to site to find something closer to what she needed.