Snapchat is a party — and startups and entrepreneurs are offering you an invitation.

Young users quickly grasped the magic of its rainbow-spewing selfies, but others are hopping on board as well. The mobile messaging service reaches 100 million users every day, including two in five Americans aged 18 to 34.

Michelle Obama joined earlier this month; celebrity DJ Khaled is one of Snapchat’s most popular users, boasting more than 6 million followers. Publishers such as the Wall Street Journal, ESPN and Buzzfeed use it to supplement their coverage. (Blue Sky Innovation is there, too, at chicagobluesky.)

Major brands are joining the platform as well. Some, like Taco Bell and 20th Century Fox, pay hundreds of thousands of dollars to sponsor the filters and lenses that reach tens of millions of users each day.

Unlike Twitter and Facebook, Snapchat doesn’t recommend who to follow based on interests or friends. Many casual users keep their Snapchat stories private, allowing access only to friends.

But some entrepreneurs use it to share behind-the-scenes at the office, to show off their products or to let their personalities fly in everyday life.

“The more under the hood you’re willing to be — about your life, about your business, about your work — the better a storyteller you are, and I think the more your fans will become loyal to you,” said Jessica Zweig, a marketing and branding consultant who previously co-founded the lifestyle website Cheeky Chicago.

Zweig said she got serious about using Snapchat a year ago, seeing an opportunity to build her personal brand and to teach her clients. Early on, she used Snapchat to share funny pictures or videos; now, she focuses on telling stories with a beginning, middle and an end. She posts snaps every day and doesn’t tone down her snaps just because her following has grown the point that unknown eyeballs are watching her.

“I want people to know the real, imperfect Jessica,” she said. “Why would I be anything other than myself?”