> I want to know what was the decision process at the moment when you first decided to start using the word "senior" on your own resume.
> ...they thought I should be using the S word!
The question suggests that you can somehow give yourself a new title which usually isn't true for people who work for someone else. Hopefully the titles that you put on your resume are your actual titles at the companies that you worked for, not something you came up with. Don't worry about calling yourself anything.
At the same time if you are able to get a promotion or apply for a senior role, that's great - go for it. It's nice that people around you are recognising your progress in some way.
Last thing, titles have meaning within any given company but are almost useless when comparing across companies. In some places to get a senior developer title, you just need to ask. Your manager then tells HR to change one cell in a spreadsheet and congrats - you're a senior software engineer. In other places you can become senior if you've been on a team for a year and everyone else has been there for a couple of months ("you have multiples of their experience, of course we can call you a senior engineer"). In those places you just need to be senior relative to the people around you. And in other companies it's a much more rigourous process with very specific criteria. There are people will decades of impressive high-profile engineering work at big companies whose title is just "Senior Software Engineer".
> The question suggests that you can somehow give yourself a new title which usually isn't true for people who work for someone else.
> In some places to get a senior developer title, you just need to ask. Your manager then tells HR to change one cell in a spreadsheet and congrats - you're a senior software engineer.
That's the "somehow". There is a very strong sense in which whole "asking your manager" thing is a mere formality—it's very unlikely to be declined if the title you're asking for is remotely appropriate (and, to be honest, often even if it isn't.) Your manager is going to be very happy that he or she has a way of keeping you happy and rewarding you for your work _without_ it coming out of their budget (the way a raise or a bonus would.)
So (at least in companies of a certain size, where this is more or less the level of formality attached to job titles), a title _is_ something you can decide to give yourself—yes, you'll want to run it by your manager to get them to ratify it for you, but that doesn't take much. Once you've decided that you want to be called by the new title, the rest is just paperwork to get it formalized.
> There is a very strong sense in which whole "asking your manager" thing is a mere formality—it's very unlikely to be declined if the title you're asking for is remotely appropriate (and, to be honest, often even if it isn't.)
That's interesting, I really didn't think that it's that common. In many companies this ranges from very difficult to completely impossible and certainly isn't just a formality. I guess that we have just been exposed to very different types of company/management.
That's very likely true. The context I was talking about probably rounds to "companies with <100 employees", or perhaps at order of magnitude larger at most. I'd imagine that it's quite different in organizations bigger than that. (Not that it's _quite_ accurate to round attitude off to size, but it's probably close enough.)
> ...they thought I should be using the S word!
The question suggests that you can somehow give yourself a new title which usually isn't true for people who work for someone else. Hopefully the titles that you put on your resume are your actual titles at the companies that you worked for, not something you came up with. Don't worry about calling yourself anything.
At the same time if you are able to get a promotion or apply for a senior role, that's great - go for it. It's nice that people around you are recognising your progress in some way.
Last thing, titles have meaning within any given company but are almost useless when comparing across companies. In some places to get a senior developer title, you just need to ask. Your manager then tells HR to change one cell in a spreadsheet and congrats - you're a senior software engineer. In other places you can become senior if you've been on a team for a year and everyone else has been there for a couple of months ("you have multiples of their experience, of course we can call you a senior engineer"). In those places you just need to be senior relative to the people around you. And in other companies it's a much more rigourous process with very specific criteria. There are people will decades of impressive high-profile engineering work at big companies whose title is just "Senior Software Engineer".