[jakecarpenter]

To me, it is about what they are able to create independently, and the value of the end product.

Senior people have made the right mistakes, wasted weeks of time, and know what to avoid, what to embrace, and what to ignore. A senior dev can understand the requirements and figure out what is important and deliver something without a lot of external input.

[mikekchar]

I'm picky. For me that's an intermediate developer. What I want to see in a senior developer is that they make everybody else on the team more effective.

As I've gotten older, I've started to appreciate how much farther a good developer can go rather than just these things. I think the kinds of things you talk about are things that most people can accomplish in 5-10 years. But how do you differentiate between that and someone with 20-30 years of experience?

Because the industry has been expanding so fast, we have perpetually been in the situation where most programmers are younger. But I don't think it will be too long before you will see half your team having 20 years of experience. If you ask yourself, "How am I going to improve after I've worked 5-10 years" and "How much better can you get" I think it is instructive.

My experience has been that you can get a lot better, but that it's very hard to see the difference from the perspective of being a junior or intermediate developer.

[zamalek]

> Senior people have made the right mistakes

This really sums it up, almost every other answer could be seen as a consequence of this.

[qznc]

Do you have to make the right mistakes yourself?

[rbanffy]

It helps with getting the muscular memory in place.

You can learn from other people's mistakes, but the pain you feel yourself will make you never forget it.