Steve Jobs stunning resignation as CEO of Apple on Wednesday and subsequent recommendation of Tim Cook to take his spot led to one big question: Who is that guy?

In Jobs' resignation letter he recommended for Cook, the chief operating officer, to take the helm of the innovative technology company. So just who is this guy that is expected to take over for a legend like Jobs?

Here are five things you need to know about new CEO Tim Cook:

He's Run Apple Before

This won't be Tim Cook's first time running Apple -- he's taken over the company in the past when Steve Jobs was out for medical leaves and most indications seem to show he's done a good job.

Jobs has battled health illnesses throughout the last decade and at each time that he needed to take a leave of absence he turned to Cook to run the company. Cook had CEO stints in 2004, 2009, and 2011 before getting the job full-time after Jobs' official resignation.

After arriving from Compaq in 1998, Cook has been counted on as one of Jobs' most trusted lieutenants and eventually became his right-hand man. Not only has he run the company before, but he's seen great success during those time periods. In 2009, Apple posted two very positive quarters under Cook's stewardship.

And since Jobs took an extended leave of absence in January 2011, Apple has released a successful iPad2, sold record number of iPhones, and even briefly topped Exxon Mobil as the world's most valuable company.

He Understands Supply Chain Management

Cook's perhaps best known strength is his supply chain management skills. CNET News noted that he is credited with completely restructuring Apple's manufacturing operations

Cook helped fix Apple's issues with its overseas factories by farming out the work to third parties, enabling the company to lower its costs and improve its profit margins.

The Wall Street Journal reported he's known as an operational genius that deftly knows how to improve the company's production efforts. One of his biggest efforts is to move inventory quickly, as Cook is said to be very against products lying around warehouses unsold.

You kind of want to manage it like you're in the dairy business, he has said. If it gets past its freshness date, you have a problem.

He Doesn't Have Jobs' Charisma

One of the things Jobs was best known for was his charisma and ability to sell the company's variety products to the masses. Jobs was known as the ultimate showman, dazzling investors and consumers alike with his annual showcases of the hottest new Apple products.

He's one of the greatest salesmen that's ever been born, Stanley Crouch, chief investment officer for Aegis Capital, told the IBTimes. He's been able to take a pulse of what will fit the market and position the product and introduce the right product. It's fantastic.

Cook doesn't appear to have that type of sales ability -- he's known as a quiet, private man good on business. That doesn't mean he won't succeed as head of Apple, but be prepared for a different approach than Jobs had.

Tim's just not a real social person, Gina Glosk, a classmate of Cook's at Auburn, told CNN Money. He's not antisocial, either. He just never seemed that interested in other people.

Cook will make his mark as being a workaholic, known for being the first in and last out according to CNN Money, and for demanding the absolute most from his employees.

He Has Jobs to Back Him Up

Despite a prolonged illness and speculation that Jobs is severely ill, Jobs plans on being involved with the company as chairman.

After his resignation as CEO, Jobs asked to remain within the company as chairman and the board is expected to accept his request. Analysts believe that Jobs could be directly involved with the company for two to five years before Cook is making every major decision without Jobs' input.

We believe Steve Jobs has his fingerprints on Apple products for the next two years, Jeffries & Co. analyst Peter Misek wrote in a note. Though many of the future products may be conceptual at this we believe Steve Jobs' vision of the Apple ecosystem goes beyond five years.

So assuming good health, Jobs could continue to help influence Apple's astonishing innovation efforts for the next few years. Cook even predicted this in a 2008 interview.

Come on, replace Steve? No. He's irreplaceable, Cook said recently, according to a person who knows him well in a CNN Money story. That's something people have to get over. I see Steve there with gray hair in his 70s, long after I'm retired.

So while critics will attack his lack of creativity, he can likely rely on Jobs for at least a few years in that department. And even with Jobs gone, he'll just have to surround himself with creative people to replicate Jobs' touch.

He's a Big Sports Fan

On the lighter side of things, Cook is apparently a huge sports fan. Cook's primary sports interest is his alma mater, Auburn University, where sponsors multiple scholarships. Cook even gave the commencement speech at Auburn's 2010 graduation ceremony.

Very little is known about Cook outside of his role in Apple besides his following of the Auburn Tigers. Cook has never publicly opined on the Cam Newton scandal at Auburn.