Many folks here are experts in their fields. For the sake of sharing knowledge, could you tell what has most influenced your career?
Was it your talent, the education you got, a person you were lucky to meet (who guided you), a book that you read, or maybe something else?
Experience (this is an answer to "What makes one an expert?", not to "How did you become an expert?" :) )
I would say by not admitting or think that you're an expert and continue to learn and ask and progress as a noob programmer.
I'd guess most people here who are experts became experts by realising how little they know, and so are unlikely to post in a thread which would indicate they are claiming to be experts.
The idea that by devoting a lot of time to all this technical stuff I will surely have less sex but still be a very significant person.
Here is a different take for you; Robert Cialdini would say that expertise is about both knowledge and trustworthiness. Here is an article, I'd highly recommend his book "Influence: The Psychology of Persuasion" if your interested in the trustworthiness element.
An "expert" is a very loosly used term. To become an expert you need all that you stated plus lots of dedication and hard work.
It is not an easy thing to become one.
The "experts" I've been lucky enough to work with have one thing in common: they have a network of other experts which they spend a lot of time with. These groups provide a kind of peer reinforcement which accelerates their learning. Whether it's by osmosis, competition, positive reinforcement or just friendly support, I can't say, but it always seems to happen in groups.
It's not uncommon to see experts leave these circles to pursue other ambitions and to wind up in relative obscurity and their expertise fading. And you very often see intermediates, who took a long time to get to that level, who join these groups and suddenly become experts in an area very quickly. As the saying goes, "you are the average of the 5 people you spend the most time with."
I think experts have great attitude on learning and perseverance. They keep learning and improving both of their theoretical and practical knowledge. They are good at focusing and also knowing how to learn from both successes and failures.
And what makes an expert remains an expert is that they do not stop once they become one. They keep updating their knowledge.
There are two types of experts: experts, and those who are not Jon Skeet. Adapted from Jon Skeet Facts
For interesting insights about how people go from "novices" to "experts" (Dreyfus Model of Skill Acquisition) and how experts actually solve problems totally differently than novices (intuition starts playing a huge role when people become more competent), I warmly recommend the book Pragmatic Thinking and Learning by Andy Hunt.
Edit, disclaimer: Using the Dreyfus model definition, I don't actually consider myself an expert (level 5), at least not yet. In some programming related skill areas I think I am currently "competent" (3) or "proficient" (4), and in others just "novice" (1) or "advanced beginner" (2).
Intuition and insights acquired after hours and hours of learning, testing, trying things out, etc.
A must read is Pragmatic Thinking and Learning by Pragmatic Andy
I saw a great answer yesterday, but it disappears today - I really like that, it was some words like:
"take the credit or critics without taking them personally"
could anyone here recall that? would you please help write that down again, I really want that.
Expert is a really subjective term. Even though I don't like to brag, I'm reasonably sure that I could be considered an expert on blinking. Beyond that, I have various levels of experience in other skills.
I know my way around UNIX/Linux/C programming because I've been doing it almost exclusively for the better part of ten years. Am I in any way an expert? Most DECIDEDLY no. I have not scratched the tip of the iceberg when it comes to exploring the full capabilities of my chosen tools. However, I can probably help you figure something out if you're stuck.
I don't think there is any such thing as an expert, except of course those of us who have become experts at blinking.
Now, that being said .. there are some people who might be considered experts at configuring certain system services .. I know some postfix gurus who could accomplish more in 10 seconds while drunk than I could in a week sober. But, this is StackOverflow, we're talking about programming, design and the understanding of what your code is actually doing to/with a computer.
Being an expert means having enough experience to know what to anticipate.
I see it as more of an art than a science, something that can only come from years of work in the trenches. Reading and studying doesn't get you there; it's more like muscle memory for your brain. An expert has been in enough situations that even something completely new feels familiar.
I would say somebody eventually becomes an expert in some area, when he keeps doing it where most people give up for misc reasons (laziness, lack of motivation etc). Eventually he learns much more than anybody else over time.