> Also companies have to advertise your salary publicly (at least around the office) for H1B.

What, really? Sorry I don't really know anything about H1B but when you say advertise does this mean it needs to be on like a bulletin board or something? Or does this mean it simply needs to be available for anyone who asks? Also, why does it need to be public?

Yep. Just enter the company name here: http://data.jobsintech.io/

There's probably a hidden benefit to this - it forces some tough questions to be asked if you find out your boss is hiring people from other countries and paying them substantially more than everyone else.

It has to be posted in 2 visible places in the place of work (typically a bulletin board). I believe the rationale behind this is to allow other employees to ask about applying for the job.

As people below mentioned, it is anonymized and typically shows the salary range and the job classification.

This is correct, it needs to be posted publicly around the office (both salary and job description). It's anonymized in that it does not have the name of the employee, but if you're one of the few around the office on an H1B ...

This is true but, fwiw, they do not necessarily keep up-to-date. I'm 4 years into a H-1B, and the amount showing on the database-scraping sites (see sibling comment), is the amount I was offered on day 1.