What does it mean to have an SSL?

Now that the whole world is using encrypted connections, our privacy becomes more important as we do more and more things online. Connections to banks, official, medical matters. On top of that, there is the Covid 19 pandemic that moved our lives even further into the online world. Nobody currently imagines that someone could eavesdrop on our transmission. Encrypted connections protect our privacy. Everyone says “we need to make it so that there is an SSL.”, but what does it really mean if something has an SSL? The following article should explain a bit.