The Chicago Cubs are in the World Series for the first time since 1945. As a result, there's been renewed interest in the curse -- or the so-called Curse of the Billy Goat.

Just what is it -- and where did it come from? We're here to provide answers.

The Cubs are four wins from breaking the curse. USATSI

1. The curse was placed in 1945

The origins of the curse are tougher to track down than you'd expect. Depending on the person telling the story, either a local tavern owner named William Sianis brought his goat Murphy to Game 4 of the World Series and was turned away, or was later ejected due to the goat's smell.

Whatever happened, Sianis was infuriated and later placed a hex on the Cubs. (Murphy, for its part, seemingly never spoke about the incident -- at least not on the record.)

2. The actual details of the curse vary

As with the story behind the curse's placing, the exact details of the curse are foggy.

Some say Sianis intended for the Cubs to never host another World Series game, some say never win another World Series, and so on. As such, again depending on the storyteller you trust, the curse might've already been snapped.

One of the most well-known moments in curse lore. Getty

3. Many, many infamous moments have since been attributed to the curse

Though the curse didn't become popular right away, it's worth noting that the Cubs did lose the 1945 World Series despite entering Game 4 up 2-1 in the series.

Since then, countless poor breaks on the Cubs' behalf have been ascribed to the Curse of the Billy Goat: from a black cat strutting past Ron Santo during a pivotal game to the Cubs running into a loaded Mets rotation. People love blaming stuff on the curse.

Let's cover two other famous incidents.

The Leon Durham mishap

In 1984, the Cubs were a victory away from the World Series, having entered Game 3 of the best-of-five NLCS against the San Diego Padres with a 2-0 lead. The Cubs would then drop Games 3 and 4.

Nonetheless, Chicago held a 3-2 lead in the bottom of the seventh of Game 5 when this happened:

That's Cubs first baseman Leon Durham allowing an easy-to-field grounder roll through his legs. The Padres tied the game on that play, and later added three other runs on their way to a 6-3 victory.

Cubs fans share the pain and emotions of many moments of crushing blows. Getty Images

The Steve Bartman incident

Flash forward 19 years, and the Cubs were up 3-0 in the top of the eighth inning of Game 6 against the then-Florida Marlins when things fell apart.

There was a runner on second and one away when Luis Castillo hit a foul ball to the left-field stands and ... well, you know what happened next. The Marlins would score eight runs and total to win Game 6, then would take Game 7 to boot.

In both cases, the Cubs were fewer than 10 outs away from the NL pennant; in both cases, an unusual defensive play served as the catalyst for a collapse.

4. The curse isn't real -- most likely

This is the part where we state the obvious: there's no evidence that the curse is real. Rather, like with most things in this arena, it seems to come down to the idea that it's only real if you believe it's real. The Cubs players probably don't believe in the curse. So, if the Cubs lose, it's not because of the curse.

Unless it's in an unusual way, then ... ah, well, forget about it. This is all for fun anyway, right?