On Saturday, a Pennsylvania man was accused of shooting 11 people to death at a synagogue in Pittsburgh in what is being considered the worst attack on Jews at worship in American history.

Before the attack, the suspected gunman posted a message on Gab, a fringe social media network launched in 2016. His use of Gab has thrust the service into the spotlight.

Here's what you need to know about Gab:

How did it start?

Gab was launched in 2016 as an alternative to traditional platforms such as Twitter and Facebook. During that time, Twitter had suspended several accounts associated with the "alt-right" movement on the same day it vowed a crackdown on hate speech.

The suspensions pushed many people to Gab, which has fewer restrictions on what content users can post compared with Twitter and other social media.

"Gab’s mission is to put people and free speech first," the service's guidelines say. "We believe that the only valid form of censorship is an individual’s own choice to opt-out."

The relaxed rules opened the door for content such as anti-Semitic posts and conspiracy theories. In August, according to The Verge, Microsoft threatened to stop hosting the social network over a pair of anti-Semitic posts, which eventually were removed.

Gab's rules say it prohibits activities such as posting illegal pornography, engaging in any illegal activity using Gab, or "calling for the acts of violence against others, promoting or engaging in self-harm, and/or acts of cruelty, threatening language or behavior that clearly, directly and incontrovertibly infringes on the safety of another user or individual(s)."

How is the suspect in Pittsburgh connected?

Before entering the synagogue, an account appearing to belong to suspect Robert Bowers, 46, posted a message on Gab: "I can't sit by an watch my people get slaughtered. Screw your optics. I'm going in."

His profile also featured multiple anti-Semitic comments and conspiracy theories, including one referenced in his last post claiming the organization HIAS, Hebrew Immigrant Aid Society, was bringing "invaders in to kill our people."

More:Who is Robert Bowers? Accused Pittsburgh synagogue shooter left anti-semitic trail

How has Gab responded?

In a statement, Gab said it was "saddened and disgusted" by the Pittsburgh attack. "Gab took swift and proactive action to contact law enforcement immediately," the service said in a statement. "We first backed up all user data from the account and then proceeded to suspend the account."

Efforts to shut Gab down

PayPal spokesman Justin Higgs said the payments service canceled Gab's account and had been in the process of ending its account before the shooting. "The company is diligent in performing reviews and taking account actions," Higgs said. "When a site is allowing the perpetuation of hate, violence or discriminatory intolerance, we take immediate and decisive action."

On Twitter, Gab said payment processing service Stripe and hosting provider Joyent were going to ban the service. Representatives from Joyent could not be immediately reached for comment. In a statement, Stripe said the company can’t comment on individual users for privacy reasons.

In a statement, Gab said the behavior from Bowers and other users isn't unique to its service. "Criminals and criminal behavior exist on every social media platform."

Follow Brett Molina on Twitter: @brettmolina23.