Today, when browsing the internet, most times your connection to the server is not secure. This means anyone can intercept and read the data you are exchanging with that particular website.
This isn’t an issue, when you are searching for the lyrics of that song you heard on the radio the other day. However, it is a big problem when you are about to buy something and you need to enter your credit card information.
Chances are, your favorite online store already has implemented everything necessary for a secure connection. But there are still a lot of websites, where this is not the case.