[boris]

They can replace you if you are just a coder. If, on the other hand, you work on an important product, acquire domain-specific knowledge, and know the code inside-out, then replacing you with someone else will be a lot harder.

Think, for example, about the folks who work on the Microsof's C/C++ compiler. I doubt any of them need to worry about their job. On the other hand, if all you did is implemented the Shutdown button for the next release of Windows then, sure, you can be easily replaced.

[earl]

That's both right and wrong. While making yourself valuable to your company is probably a good idea, you have to be working for an employer smart enough to realize it. Which is, in my experience, not most large employers.

In the layoffs I've been through, the people let go were almost random WRT how valuable they were as employees or developers. What was rewarded was managing up.