Venus and Serena started playing tennis at a young age, as their father Richard was determined to make one of his "trophy daughters" become a world-renowned female tennis player.
They have three other sisters, Isha, Lyndrea, and Yetunde, who have always supported Venus and Serena in their careers. In 2003, Yetunde was tragically murdered in Los Angeles.
All five Williams sisters were raised by their mother as Jehovah's Witnesses.
Both were trained at the renowned Nick Bollettieri Tennis Academy. However, their father Richard withdrew them from the academy upon hearing racially discriminatory comments from parents at the school's Junior Tournament. He also withdrew them from junior competition when Venus was 12 and Serena was 11.
Subsequently, their father Richard began coaching both of them at tennis courts in Compton.
Venus turned professional at the age of 14. In her first match, she defeated Shaun Stafford, the then 58th-ranked player in the world. A year later, Serena followed her sister into professional play.
Venus signed her first commercial deal with Reebok worth "eight figures" when she was just 15 years old. Shortly after, Serena also secured a similar contract with Puma.
Venus and Serena respectively won the "Most Impressive Newcomer" award in 1997 and 1998. In 2000, they were named the "Best Doubles Pair of the Year" at the awards ceremony.
At the 2000 Sydney Olympics, Venus won the gold medal in women's singles. Both Williams sisters won the gold medal in women's doubles at the 2008 Beijing Olympics.
The Williams sisters have faced each other in the Grand Slam final four times, including the French Open, Wimbledon, and the US Open in 2002, and the Australian Open in 2003.
Serena once won four Grand Slam championships within 12 months (Roland Garros 2002, Wimbledon 2002, US Open 2002, and Australian Open 2003). This achievement has only been accomplished by four other female tennis players in the world.
They have met 20 times, with each winning 10 matches.
However, Serena has defeated her older sister in Grand Slam tournaments more often, winning 5 out of 7 encounters.
As of now, Serena has won 10 Grand Slam titles while Venus has received this prestigious award 7 times.
Venus is at the forefront of the campaign for equal prize money for male and female tennis players. In 2006, she was appointed as a UNESCO ambassador for issues related to women.
After campaigning for equal prize money between the genders, she became the first female tennis player to earn the same prize money as male players at Wimbledon when she won the tournament in 2007.
Serena is the highest-earning female athlete in the world, with earnings totaling $24 million USD. Venus ranks second with $23 million USD.
Both Williams sisters starred in the reality TV show "Venus and Serena for Real," which closely followed their lives both on and off the tennis court.
Serena has also appeared as a guest star in TV shows such as ER and The Simpsons.
Both sisters have launched their own fashion lines, with Venus's fashion brand named "BeVen" and Serena's brand called "Aneres."