The Harry Potter storyline secrets we never knew existed until now.

It’s hard to believe, but as of this week, it’s been 20 years since the Boy Who Lived came into our lives and his story of Harry Potter going from living under the stairs of his aunt and uncle’s house to becoming one of the most brilliant wizards of his time took over the imaginations of parents and children around the world.

In celebration (and with the help of super fans), we take a look back at three of the best storyline secrets weaved throughout J.K Rowling’s masterpiece story.

The number 13 is very, very significant.

In case you missed it, the number 13 features prolifically throughout the Harry Potter series. For starters, Sirius Black was imprisoned (wrongfully, mind you) for the murders of 13 people.

Then there's also the 13 years Voldemort spent living without human form and the fact that his wand is 13 and a half inches long.

And if that's not enough, there are two major instances in which this uneven number ultimately comes to claim the lives of not one, but two major characters.

One year on Christmas Day at Hogwarts, Divination teacher Professor Trelawney is invited to sit at a table of what appears to be 12 people but refuses, stating that the first person to stand from a table of 13 people will die.

At the time, the comment seemed pretty, well, Professor Trelawney-esque and no one gave it much notice.

What they couldn't have known though, was that thanks to Ron's pet rat Scabbers actually being Peter Pettigrew, there were already 13 people at the table. And the first to stand that day was none other than Professor Dumbledore.

During another dining table gathering, this time at the Order of the Phoenix headquarters, 13 people gather once more, still seemingly unaware of the number's significance. The first to rise from this discussion, as you may remember, was Sirius Black.

MIND BLOWN, PEOPLE. MIND BLOWN.

Snape was giving Harry clues about Lily from the very start.

From their first encounters within the potions classroom, Snape seemed to have it out for Harry, and the feeling was swiftly reciprocated.

But as we all found out in the moments before and after Snape's death, Hogwarts' Potions Master had not only spent the better part of his life in love with Harry's mother, Lily but had also fought to protect her from Voldemort - something he failed to do.

In their first class together, Snape asked Harry the seemingly innocent question, "What would I get if I added powdered root of asphodel to an infusion of wormwood?"

And like many things in the Harry Potter series, the meaning is deep.

To begin, asphodel is a type of lily. When translated, its traditional meaning is "my regrets follow you to the grave."

As for the meaning for Wormwood, you ask? "Absence."

When adding one to the other, as Snape asked, you would mean something along the lines of "my regrets of not protecting Lily will follow me to the grave."

Harry's wand was always a sign of things to come.

Leaving its connection with Voldemort aside, from the moment he stepped inside Ollivander's to purchase his first wand, it became clear that Harry was going to have to one day die to eventually beat the Dark Lord.

The 11-inch wand, which chose Harry, was made from Holly, a tree which in the Celtic tree calendar represents the eight month of the year (in which Harry was born, of course) and it's also known as The Tree of Sacrifice - meaning Harry was always going to have to give his life to sacrifice breaking the bond between he and Voldemort.

And with all three of their wands being made from Celtic-rooted woods, the friendship of Ron, Hermione and Harry were all guaranteed from the start, because types of wood can be best friends too, you guys.

What were your favourite Harry Potter moments? Let us know in the comments section below.