Image copyright Getty Images Image caption L-R: Alexander McQueen, Michael Kors, Chanel, Nina Ricci, Carolina Herrera

There's not much you can be sure of in 2018, like whether you'll ever use your gym membership or stop binge-watching box sets.

What you can be certain of is what to wear, as fashion houses have already been setting out spring and summer's biggest trends.

From feathers to clear plastic, purple to polka dots, there were a wide variety of styles on display at London, Paris, Milan and New York Fashion Week.

With loads of Christmas sales to choose from, here's how you can get ahead with six trends to look out for next time you hit the shops.

50 shades of lavender

Image copyright Getty Images Image caption L-R: Dries Van Noten, Michael Kors, Max Mara and Atlein

Every time the Spring/Summer shows come around, a new pastel palette takes over and this year is no different.

If you want to be on trend in 2018 then it's all about different shades of purple.

Lavender is taking over from "millennial pink" as the next must-have colour and was shown in floaty dresses, structured suits and metallics.

Michael Kors, Valentino, Bottega Veneta and Erdem were all over this look at fashion week.

Double dark denim

Image copyright Getty Images Image caption L-R: Tibi, Mugler, Nina Ricci, Alexander McQueen

Britney Spears and Justin Timberlake called and they want their double denim back.

The fashion houses are taking a nod from 00s fashion with matching denim ensembles, this time in a deep indigo shade.

The embellished and ripped jeans of the last decade make way for a more sophisticated and polished look.

Fendi, Tom Ford, Chloe and Nina Ricci rocked this look on the catwalk.

The plastics

Image copyright Getty Images Image caption L-R: Valentino, Chanel, Burberry, Salvatore Ferragamo

This is a futuristic fashion trend that's taking over from vinyl, which was all the rage last season.

Trench coats, knee-high boots and handbags all made an appearance in shiny see-through plastic.

This might be the most practical look of 2018 - waterproof and easy to clean!

Chanel and Calvin Klein were big champions of this look, along with Balmain and Marc Jacobs.

Fringing and feathers

Image copyright Getty Images Image caption L-R: Nina Ricci, Celine, Topshop, Balmain

It's not the most daytime look, but if you're looking ahead to a big event in 2018 then think fringing and feathers.

This glamorous and dramatic look was spotted all over the catwalk and is already popping up on the high street.

You can be on trend without going all out by choosing a feather trimmed bag or skirt, or perhaps a fringed top.

This look was big at Dior, Loewe, Celine and Salvatore Ferragamo.

Polka dots in reverse

Image copyright Getty Images Image caption L-R: Junya Watanabe, Jason Wu, Carolina Herrera, Blumarine

Black on white polka dots provided a twist on a classic look at the Spring/Summer shows.

If there was one trend that works in all seasons it's this one, so if you invest in a polka dot top or dress you can wear it all year round.

This is a look that took over from florals as the go-to spring print at fashion shows.

Carolina Herrera, Jason Wu and Alexandre Vauthier all showcased this print.

The trench 2.0

Image copyright Getty Images Image caption L-R: Dior, Maison Margiela, Celine, Alexander McQueen

The wardrobe staple trench coat gets a refresh in 2018, complete with new cuts, accessories and embellishment.

Each designer interpreted the trench coat design differently, so there's lots of looks to choose from.

If you feel like updating your trench, you can add embroidery like Alexander McQueen or Loewe's feathering.

Dior added a matching playsuit underneath, whilst Celine complemented the classic design with a hint of red.

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