Sometimes, you stumble upon a song you haven't heard in a while, and go "oh yeah, I remember this, this exists". It sparks a memory of times past, and of the emotional equilibrium (or lack thereof) that went along with them. It might be a strong memory, or a passing one. Either way, the memory chord is struck.
Most of the time, nothing much comes of it. You just remember the memory, and then move on. It is the way of things. The world is big and contains many memories.
Sometimes, you stumble upon a song from an artist you only ever heard the one song from. Out of curiosity, you decide to check if there were any other songs made back in the days, and if they are anything like what you've heard so far. After some listening, you discover that there is and that they aren't. In fact, the rest of the artist's production is nothing like that one song; it is an unexplored field of newness that awaits personal discovery.
At times, this is how new favorite artists are found.
To be sure, this process has been made simpler through systems of file sharing - whether they be spotify or discography torrents. Any time you remember something, the option is always there to shore up everything this person has ever done and peruse. All that is needed is a memory, and a name.
It is one of those things that is easy to take for granted. But it is useful, nonetheless.