Levels aren't standardized in industry, but they are inside a company. They impact pay bands and other things. IC1 sounds like it's for new grads. Junior doesn

Levels aren't standardized in industry, but they are inside a company. They impact pay bands and other things. IC1 sounds like it's for new grads. Junior doesn't seem to be a popular title in the bay area. One or two are probably Senior levels. I find it useful for how they change. Work complexity grows, timelines go from some tasks to multi-year projects, and you are expected to work more outside your team and mentor engineers. It doesn't really give you a path to get promoted though.