On 28 October 2015, Microsoft founder Bill Gates turned 60. During his life he’s been many things: a precocious student, an aggressive founder of a huge company, a super-smart coder and now a philanthropist aiming to rid the world of malaria.

What’s been consistent in everything Gates has done, though, is his drive and will to succeed. As a businessperson, Gates looks to the outside world as if he knows no fear, taking on competitors, the US Department of Justice and now a disease.

There have been many moments in Gates’ life that have shaped not only his future, but also that of the computer industry. No single person – not even Steve Jobs – has made a bigger impact on computing. Arguably, Gates’ work has affected more people than any other person in the 20th century.

We’ve picked out the ten moments we think encapsulate Bill Gates, both good and bad, and his impact on the world.

1975: Gates starts Microsoft

“By the age of 20 Gates and school friend Paul Allen were already running Microsoft – or rather “Micro-Soft””

Although they didn’t register the trademark until the following year, by the age of 20 Gates and school friend Paul Allen were already running Microsoft – or rather “Micro-Soft”, as they were calling it at the time.

The two, who had been friends since school, had been obsessed with computers at a time when they were the size of cars and you worked with them remotely via teletype.

Fortunately, they went to a school that had the funds to install a teletype for computer access – a rarity in the 1960s – although pupils had to pay for computer time over and above their “free” allocation. Allen was so obsessed that, as Gates revealed in a 1995 interview with Time magazine, he wasn’t allowed to graduate until his parents had paid off the $200 bill for extra computer time.

Gates and Allen had already started another company before Microsoft, called Traf-O-Data, but it was the opportunity to create a version of BASIC for the Altair 8800 from Micro Instrumentation and Telemetry Systems (MITS), which the magazine Popular Electronics described as the “world’s first minicomputer kit to rival commercial models”, that really spurred their business careers. To sell the product, they needed a company – and Microsoft, without the hyphen, was born.

1976: Gates sends “the Open Letter to Hobbyists”

Altair BASIC did well, but not well enough for the budding entrepreneurs. At a seminar for the legendary Homebrew Computer Club, a paper tape with the code for Altair BASIC on it disappeared – and at the next meeting, 50 copies of the tape were freely handed out.

“Code was something you shared, not sold.”

This was entirely in accordance with the culture of computing at the time. Code was something you shared, not sold – but Microsoft was receiving a royalty on every copy of BASIC shipped by MITS. And, although MITS was selling hundreds of Altairs per month, only a few tens of copies of BASIC were going along with them.

Appalled by what he saw as the theft of Microsoft code, Gates wrote an open letter to the hobbyist community, which appeared in the Homebrew Computer Club newsletter. He pointed out that “most directly, the thing you do is theft” – setting the tone for the battle between commercial software and piracy that goes on today.

1977: Gates gets arrested, and the infamous “mugshot” is born

If Gates was determined to ensure that computer hobbyists obeyed the law, he was less interested in obeying it himself. Twice, in 1975 and 1977, he was arrested for speeding, although some reports embellish this by adding in driving without a licence and running a stop sign.

“The second arrest generated one of the most famous images of Gates.”

The second arrest generated one of the most famous images of Gates. Sporting a floral shirt, curious “casual” sweater and a pair of glasses that could only come from the 1970s, the 21-year-old Gates’ mugshot makes him look like a teenager, complete with a boyish grin that suggests he really doesn’t care about the arrest.

However, the mugshot has had a bigger influence than you might think. Ken Fisher, editor-in-chief of Ars Technica, noticed that the default image silhouette used in Outlook 2010 bore a remarkable resemblance to the mugshot. We have no way of verifying this, but the similarities are certainly there to see.

1977: Gates officially leaves Harvard

“Harvard had one important impact on Gates’ life: it was where he first met Steve Ballmer.”

Harvard’s student newspaper, The Harvard Crimson, once named Bill Gates the university’s “most successful dropout”, and it’s hard to disagree. Gates’ record at Harvard was, to say the least, patchy: initially enrolling in 1973, he attended for a few semesters here and there before formally dropping out in 1977, just two semesters short of graduating. He got an honorary degree from the university in 2007, when he told the audience for his speech that “I’ve been waiting more than 30 years to say this: Dad, I always told you I’d come back and get my degree.”

However, Harvard had one important impact on Gates’ life: it was where he first met Steve Ballmer, who was to join Microsoft in 1980 and rise to being both Gates’ best friend and CEO.