He can fix your eyes

Paul is an ophthalmologist and often says he wouldn't have left his practice if he didn't think he could try to change Washington. Paul still practices, performing pro-bono eye surgeries on low-income residents in Kentucky and abroad. Last year, he traveled to Guatemala -- with a bodyguard named Axel -- and performed cataract surgeries. The trip also showcased Paul's command of Spanish, which he learned growing up in Texas.

He first grabbed the D.C. spotlight thanks to drones and Jane Fonda

Paul shot to fame in Washington after conducting a nearly 13-hour filibuster in opposition to President Obama's drone policy and the nomination of John O. Brennan as director of the CIA. His filibuster had its moments, including a little help from his friends -- and likely foes on the campaign trail -- Sens. Ted Cruz (R-Tex.) and Marco Rubio (R-Fla.). Rubio even quoted Jay Z on the Senate floor. Paul talked about the notion of dropping a drone on Jane Fonda.

He likes to tweet -- and troll 

Paul likes to tweet -- a lot. He (or at least, his account) also likes to troll people.

During the State of the Union:

When Marco Rubio weighed in on the shift in Cuba policy:

On Valentine's Day:

He airs his grievances

On Festivus, the "Seinfeld"-born holiday, individuals are supposed to share with their loved ones all the ways their nearest and dearest have disappointed them in the previous year. Few do it more enthusiastically than Paul, who lets his complaints fly each Dec. 23. Here are a few.

He literally got a shot in the arm

Paul waded into controversy when he suggested that vaccines should be voluntary. He later backed off -- and got a shot.

He's reaching out to black voters

Rand Paul at Bowie State University in Maryland. (Jose Luis Magana/AP)

Paul has been trying to court black voters, saying that the Republican Party needs to bring in more young and minority voters. It hasn't always gone well. Two years ago, he spoke at Howard University, a trip that was filled with fumbles. They included bungling the name of Edward Brooke, the nation's first black senator to be elected since Reconstruction, and attempting to explain a controversy over remarks he made on the 1964 Civil Rights Act. In an interview with MSNBC, Paul mused about possibly changing one provision of the law; he later adamantly stated he never wavered in his commitment to the landmark legislation. He fared much better during a speech at Bowie State University last month and seemed to have found his footing when it comes to talking about race.

He has no undergraduate degree

Paul went to Baylor University. (Orlin Wagner/AP)

Paul got his medical degree from Duke University and has talked about having a biology degree. He actually has no undergraduate degree; he attended Baylor University but his MCAT scores were high enough that Duke accepted him without an undergraduate degree. It's a policy the school has since changed.

He isn't the first Paul to run for president

The father. (Scott Olson/Getty Images)

Paul is the scion of one of the nation's most famous libertarian families: His father is two-time presidential contender and former U.S. Congressman Ron Paul. The two men are close, and Ron gave Rand his first foray into politics when the son managed one of the father's Senate campaigns. But right now they are heading in opposite directions; in January, Ron talked about seceding from the United States. His son wants to lead it.

Sen. Rand Paul, (R-Ky.), who announced he's running for president in 2016, is known for his belief in limited government. Here his take on Obamacare, the Constitution and more, in his own words. (Julie Percha/The Washington Post)

Related reading:

Rand Paul announces presidential run

Meet the people who will try to get Rand Paul elected president in 2016

Can Rand Paul troll his way to the White House?

This post has been corrected. Ron Paul was not a Senator.