One sentence sums up why millennials are flocking to Nike, Under Armour, and Lululemon

Millennials are tricky customers.

They tend to spend money on experiences rather than clothing and are picky about apparel in general.

We already know that consumers gravitate towards purchasing athletic wear over traditional apparel, since athleisure clothing lends itself to experiences and activities. But which clothing companies reign supreme in such a saturated market?

Jeff Fromm, consultant from research company FutureCast, believes Lululemon, Nike, and Under Armour have managed to differentiate themselves from other companies.

Fromm writes on a Forbes contributor post that it's because all three brands sell more than just apparel; they sell communities and ideologies, too.

"Unlike the less successful retailers who entered the space, these brands prove their missions and have the communities to back them up," he writes.

"Nike is based on the idea that if you have a body you are an athlete. Under Armour focuses on making athletes better through passion, empowerment and design. Lululemon's manifesto centers itself on creating a community of health, mindfulness and living a life of possibility," he writes earlier in the post.

Fromm also writes that other brands without such deeply embedded ideologies have faltered, specifically pointing toUrban Outfitters' Without Walls, whose Internet presence mysteriously thinned out in the fall.

RELATED: Brands Americans can't stand

Having a community built into a brand is especially appealing for young people.

In fact, community driven brands, as a whole, have been thriving lately, even beyond the apparel industry (think: SoulCycle and CrossFit). This — coupled with the fact that millennials like to spend on experiences —is partially why young people are willing to spend money on fitness classes, too.

"What seems consistent is building — and I say this word with some trepidation — kind of these authentic, community-driven brands seems to be the big lesson here," Jason Kelly, author of Sweat Equity and New York Bureau Chief at Bloomberg, told Business Insider last month. "That people do react in a lot of ways to something that they feel they want to be a part of, that their friends are a part of, and that's a brand that really understands them and caters to them, and people like them."

This is emphasized in Nike's run clubs, Lululemon's in-store yoga classes, and Under Armour's digital running challenges.

Beyond actual physical community, these three brands foster a sense of community that people can be a part of by wearing their respective clothes. Fromm points to Lululemon, specifically, as an example of this.

As the athleisure market continues to grow, more and more brands keep popping up, and if Fromm's argument remains true, then only brands with strong, distinct mentalities and clear senses of communities will survive millennials' discerning tastes and wallets.

One brand that has gained some attention is Outdoor Voices, which prides itself on its non-competitive attitude — it's inadvertently become the anti-Nike.

Additionally, other brands, like Athleta and Bandier, offer in-store classes, as though to capitalize on the community component.

RELATED: The best Nike products to buy

For Fromm's full post on Forbes, click here.

NOW WATCH: How $98 Lululemon yoga pants compare to cheaper alternatives

More from Business Insider
Beyoncé is giving Nordstrom a much-needed boost
Nike is facing unprecedented headwinds
We polled 110 teenagers on which brands they love and hate in 2016

SEE ALSO: Millennials are abandoning restaurants for an unexpected place