Little-known purpose of red Christmas light revealed as people only just realising what it actually is

Christmas is just around the corner, which means many of us are digging out our decorations and starting the mammoth job of putting up the tree.

If you're about to do yours - or if you've already got the decs up - there's a good chance you'll have come across a single red Christmas bulb somewhere among your fairy lights, but do you know what it's used for?

Many people have started putting up their Christmas decorations (Getty Stock Photo)

If you thought the red bulb was a spare or a replacement, then you're not the only one.

In fact, many people have no idea what the little bulb is for and often assume it's a spare just in case one breaks or cracks.

But it turns out it has a completely different use.

It's actually used to give the lights a flickering appearance if there's no remote on the battery pack or plug.

All you have to do is remove one of the regular bulbs and replace with the red one, which interrupts the circuit and results in the lights 'blinking'.

Have you spotted a red bulb within your fairy lights? (Getty Stock Photo)

So how does it work?

Well, according to Family Handyman, the red bulb has an extra piece of metal inside. They explain that when the filament within the bulb gets hot, the strip bends and the lights go out.

Once it cools again, the light turns back on, creating a flickering pattern.

It's worth noting that lights with 100 or more bulbs will often have more than one circuit.

If you're using lights with 50 bulbs, you can pretty much place the red bulb anywhere and see all the lights blink at once.

But on larger packs, only the lights within the same circuit will flicker.

The red bulb causes the lights to flicker (Getty Stock Photo)

In other festive news, if you failed to properly pack away your Christmas lights last year, you'll know how frustrating it can be to unravel them.

Luckily, one woman has come up with a genius way to store fairy lights and stop them tangling.

TikToker Tanya has all sorts of helpful hacks around the home, and learning the Christmas ones is really useful this time of year.

All you'll need a shoebox and a bit of tape. Then, simply wrap the lights around the box (slowly does it) and tape them in place.

Cut a little slit in the top of the box so you can slip the plug and power unit inside.

With that secure, you now have an almost completely empty box which is already dedicated to Christmas decorations, so it's a good place to store your baubles until next Christmas.

Genius.