The word "senior" varies by level for different job tracks -- for some it's not even until L7 (or at least it was this way in the past).

But my understanding is that, across most job tracks, it's expected that everyone should get promoted to L5 eventually just by working hard.

While it's never expected to get to L6. You might get to L5 and just stay there forever. L6 requires a certain level of achievement that they don't expect everyone to be able to achieve. That's what sets it apart.

So it makes sense this is the level where they're closing the gate even more.

I recently heard but did not verify that L4 is now terminal instead of 5 which makes a ton of sense to me and also puts this new tidbit in context.

It’s been a few years since I had access to the data, for for a long time 6+ made up about 10% of ICs

"Senior SWE" is not a senior position; I think we all know that.

It hurts, but you're not wrong :(

Senior Software Engineer is indeed the title for L5 SWE at Google. However, whether a "senior software engineer" title is considered "senior" in a general sense these days is debatable.

I noticed this.

Not Google but I worked at a mid-size US based company briefly last year.

The team was junior but senior in titles and highly opinionated, that was why I ended up leaving as nothing was getting done. Not last week I got a bunch of LinkedIn updates saying “Congratulate X being promoted to Senior/Staff/Principal Engineer”.

The grads I worked with who were good and what you expect for a grad where getting promoted to senior’s and the seniors who were ok, maybe a little inexperienced were getting promoted to staff.

I think roles mean nothing these days. They’re devalued and only exist for people to move up in to the next pay band.

What I consider senior from 15-20 years ago is staff engineer now and principal today feels like someone at the top of senior 15-20 years ago.

There are a lot more people in the field today so the standards have dropped as is necessary. Principal is top x%, senior is top y%, etc. It's not capability based.

Given that L5 is a terminal position, and thus a mark of seniority, the title of “senior” would appear to be the correct title.

Yes, but that's also title inflation

Eh, you're a senior SWE at L5 in a lot of companies, but L6 is definitely where you start to be seen as closer to management in the chain than your typical IC. You start being involved in calibration for example.

L5 is mostly about reaching greater depths with your skills as an L4, L6 is more about gaining breadth that isn't guaranteed just by being an L5 for a while

L5 used to be the first terminal level, meaning that you could stay at L5 for as long as you liked as long as your performance was good. (Nowadays that so-called "growth expectation" has gotten a lot fuzzier, with some orgs letting people stay at L4 or even L3 for many years.)

So L6 was the first elective level. Anyone who reached it did so by opting in, rather than just going with the flow. That is why it carries a bit of weight.

All this was more true back in the 2000s. (Source: me, ex-Googler, 2003-22.)

You are correct. L5 is senior, L6 is staff, L7 is senior staff. Source: am L6.