(CNN) -- Lance Armstrong, seven-time winner of the Tour de France, on Thursday announced he would no longer contest charges that he doped his way to victory. The 40-year-old legendary cyclist still maintains he's innocent.
Here are five key questions and answers to help you better understand the complicated development in a longstanding controversy involving one of the most achieving endurance athletes of all time:
1. What has Armstrong been accused of and what does he say?
The United States Anti-Doping Agency charged Armstrong with doping and trafficking of performance-enhancing drugs. Several members of Armstrong's former team also were charged.
Armstrong vehemently maintains that he has never doped and that he has never failed a drug test. He accused the USADA of pursuing an "unconstitutional witch hunt" against him and he maintained the USADA does not have the right to prosecute him. On Monday, a U.S. Federal Court ruled against the cyclist.
The cyclist explained Thursday that he would no longer fight the charges, saying that the ongoing battle had taken a toll on him personally and on his family.
2. What does Armstrong's decision not to contest USADA's charges mean?
The U.S. Anti-Doping Agency is the body responsible for monitoring drug testing for U.S. Olympic and Paralympic sports for athletes in and out of active competition. USADA says Armstrong's decision not to contest the charges means there will be no hearing on the actual charges and as a result he will receive "a lifetime period of ineligibility and disqualification of all competitive results from August 1, 1998, through the present."
3. What about Armstrong's record seven Tour de France titles?
Right now it's unclear what this will mean for the seven wins. USADA says that Armstrong will be "disqualified from any and all competitive results obtained" since August 1, 1998.
USADA says that Armstrong will be stripped of seven Tour titles, all of his other titles and the bronze medal he won at the 2000 Olympics. Travis Tygart, USADA's CEO, told the New York Times that it also means that Armstrong cannot coach or have any "official role" with any Olympic sport or other sport that adheres to the World Anti-Doping Code.
However, the International Cycling Union, based in Switzerland, the world governing body for cycling, said Friday that it will not act until it hears directly from USADA, suggesting it wants to see more details on the case.
It's unclear if USADA has the power to "strip" Armstrong of his Tour de France titles or if that jurisdiction lies with the UCI.
Officials with the Tour de France are waiting before they comment on Armstrong's case, the Washington Post reports.
On his site, Armstrong wrote: USADA cannot assert control of a professional international sport and attempt to strip my seven Tour de France titles. I know who won those seven Tours, my teammates know who won those seven Tours, and everyone I competed against knows who won those seven Tours.
4. Where does this leave the sport of cycling?
There have been numerous other allegations of doping against cyclists. The Internet magazine Slate recently examined how many cyclists dope compared with other athletes. Tour de France winners Floyd Landis and Alberto Contador were involved in doping cases and had their Tour titles taken.
Just last month, a French Tour de France cyclist was suspended while an investigation into doping could take place. In Armstrong's case, USADA said it had numerous witnesses ready to testify at a hearing that Armstrong had indeed doped. Those witnesses include some of his teammates, such as Tyler Hamilton and George Hincapie, legends in cycling.
Hamilton told CBS's "60 Minutes" in May that he helped Armstrong dope. Hamilton's credibility has been questioned because he himself doped, and has been stripped of a 2004 Olympic time trial gold medal.
5. What does this mean for Armstrong's legacy?
Armstrong is famous for his work on behalf of cancer research under his Livestrong Foundation which he says has raised $500 million. The foundation will turn 15 in October. An online petition has popped up to rally for Armstrong. Nike, which has a contract with Armstrong, announced Friday that it will stand behind the athlete. Anheuser-Busch also said it's supporting the pitchman of its Michelob-Ultra brew. Though many others feel that fans who believe he did dope shouldn't forgive him.
Only time will tell whether Armstrong will remembered for all the good he has done or whether, as some believe, he cheated his way to victory. ESPN's Darren Rovell contemplated how tough it will be for many to decide what they think of Armstrong. Rovell retweeted a picture of one angry fan's take on Livestrong's iconic yellow bracelet.