Image via iStock.

There used to be a time when foundation, mascara, a little blush and lipstick was considered a full face of makeup. Alas, no more. Now we have brows to fill in, noses to highlight, cheeks to contour and skin to prime – and for some, that’s just for running out to the shops.

Primer in particular really seems to have hogged the spotlight in recent years. There seems to be a primer for just about every part of your body – but are they actually necessary?

What exactly is a primer?

Let’s start with the basics.

“A primer preps the skin to ensure your foundation lasts longer and looks smoother and more flawless,” says Kate Squires from the Napoleon Perdis Creative Team.

A primer is great for creating flawless looking skin.

Some primers also have additional benefits like brightening or calming properties and offer added hydration.

The 'flawless' look is achieved by the primers essentially working as a barrier between your skin and foundation, stopping your foundation from absorbing into the skin and clogging your pores.

"The barrier smoothes the texture of the skin, minimises the appearance of pores, fine lines, scars, dehydration and unevenness," Squires says.

RELATED: What is a skin finisher and do I need one?

"It also means your foundation glides on more smoothly and is easier to apply, as well as preventing your skin from absorbing the foundation throughout the day."

Do we really need ALL the primers?

It's not just your face that primer is made for - you'll also find products promising to prime your lips, eyelashes and even eyelids. But which are must-have and which are not?

Face

"Face primers are a must, especially if you're wearing foundation. However if you're only wearing a little concealer and blush, a face primer will still ensure the product glides over your skin smoothly and lasts the distance," says Squires.

"I recommend a face primer for every time you use makeup. I am a fan of ones that add luminosity to the skin or boost radiance, especially in winter," she says.

"These types of primers will give your skin that extra lustre and polish and help to combat the signs of dehydration. As an artist, I'm also a fan of a primer that minimises the appearance of large pores."

Verdict: YES. (Post continues after gallery.)

The Glow team's favourite primers

Laura Mercier Hydrating Primer, $45,

http://www.theglow.com.au/glow-guide/laura-mercier-primer

Iluka Anti-ageing Illuminising Pearl Primer, $29.99

Napoleon Perdis

Napoleon Perdis Auto Pilot Pre-Foundation Skin Primer http://www.theglow.com.au/glow-guide/napoleon-perdis-auto-pilot-skin-primer/

Eyes

There are TWO priming products for your eyes - concealer primers and eye primers.

"Concealer primers prep the skin under your eyes and eye primers prep your lids for shadow or liner application," Squires explains.

"If darkness or dehydration under the eyes is a concern, a concealer primer will ensure your concealer sits as smooth as possible, last the distance and keep the areas hydrated throughout the day."

RELATED: 4 easy ways to banish under-eye bags

And if you love your eyeshadow, then eye primers can be a good investment.

"They're great as they increase the blendability of your shadows and prevent them from creasing,  however they're not essential for creating a good eye," says Squires.

Verdict: OPTIONAL.

Lips

"Lip primers are essentially lip conditioners in disguise," explains Squires.

"I 100 per cent believe in treating the lips as this will ensure your lips are prepped and ready when it comes to applying your lippie."

But that doesn't mean lip primers are always the best solution.

RELATED: Why balm stains are the lazy (and hungry) woman’s lipstick.

"I've never met a lip primer that actually makes lipstick look smoother or last longer," says Squires.

"Yes, if you hydrate the lips and remove dry, flaky skin your lippie will sit better, but this is just conditioning the lips. Always have a good balm or condition in your makeup back, but leave the priming for the eyes and face," she says.

Verdict: NOT WORTH IT.

Lashes

Remember that stage where every mascara was double-ended and came with a bright white priming end?

"Lash primers aren't necessary for everyday wear, but can be used to create a dramatic effect with your natural lashes," says Squires.

Verdict: OPTIONAL.

What's the best way to apply primer?

Unfortunately for best results, it's not your fingers.

Firstly, make sure skin is f