So this post by @Cyanide had me wondering, what does it take to be a senior developer, and what makes one more senior than the other?

You see, I started at my current company about three or four years ago. It was my first job, and I got it before even having started any real programming education. I'd say that at this point I was beyond doubt a junior. The thing is that the team I joined consisted of me and my colleague, who was only working 50%. Together we built a brand new system which today is the basis on which the company stands on.

Today I'm responsible for a bunch of consultants, handle contact during partnerships with other companies, and lead a lot of development work. I'm basically doing the exact same things as my colleague, and also security and server management. So except for the fact that he's significantly older than me the only things that I can think of that differentiates the seniority in the team are experience and code quality.

In terms of experience a longer life obviously means more opportunities to gather experiences. The thing is that my colleague seems to be very experienced in 10 year old technologies, but the current stuff is not his strong side. That leaves code quality, and if you've ever read my previous rants I think you know what I'm thinking...

So what in the world makes a person senior? If we hired a new colleague now I'm not sure it'd be instantly clear who should guide and teach them.