A Look Back at the Life and Legacy of Microsoft Co-Founder Paul Allen "I am heartbroken by the passing of one my oldest and dearest friends," Gates said in a statement

Microsoft is today a household name all around the world. Founded by Bill Gates alongside Paul Allen, the tech giant continues to lead the software market amid rising competition. Allen, who convinced Gates to start the world's biggest software company, died on Monday afternoon from complications of non-Hodgkin's lymphoma. He officially resigned from his position on the Microsoft board of directors on November 9, 2000, and remained as a senior strategy advisor to the company's executives.

Many tech leaders have taken to Facebook and Twitter to mourn the loss of billionaire philanthropist who also successfully managed his multibillion-dollar investment portfolio including technology and media companies, scientific research, real estate holdings, private spaceflight ventures, and stakes in other companies.

"I am heartbroken by the passing of one my oldest and dearest friends," Gates said in a statement.

Here we take a look back at his life and creation of a software behemoth that's still going strong.

Microsoft's Success:

In 1980, after Microsoft had committed to deliver IBM a disk operating system (DOS) for the original IBM PC, although they had not yet developed one, Allen spearheaded a deal for Microsoft to purchase QDOS (Quick and Dirty Operating System), written by Tim Paterson, who, at the time, was employed at Seattle Computer Products. As a result of this transaction, Microsoft was able to secure a contract to supply the DOS that would eventually run on IBM's PC line. This contract with IBM proved the watershed in Microsoft history that led to Allen's and Gates' wealth and success.

Filmmaking Bug:

Allen and his sister Jody Allen together were the owners and executive producers of Vulcan Productions, a television and film production company headquartered in Seattle within the entertainment division of Vulcan Inc. Their films have received various recognition, ranging from a Peabody to Independent Spirit Awards, Grammys and Emmys.

Big-time Philanthropist:

Allen has always been a charitable person and hence he did not shy away to show his support for noble causes. He gave more than $2 billion to causes such as education, wildlife and environmental conservation, the arts, healthcare, community services, and more.

Party Host:

Every year in May, Allen used to throw a themed party at Cannes Film Festival, often on his mega yacht, Octopus. The celebrity-studded parties had performances from Allen and his band. In 2015, Allen decided to throw a Bollywood-themed party inside Octopus yacht in Cannes. The party was attended by more than 200 popular celebrities.

Art Lover:

An active art collector, Allen gifted more than $100 million to support the arts. On October 15, 2012, the Americans for the Arts gave Allen the Eli and Edythe Broad Award for Philanthropy in the Arts. He also loaned out more than 300 pieces from his private art collection to 47 different venues.