European here - what's it mean to vest shares? It sounds like some sort of stock options became unlocked? I haven't heard of this thing before, just of stocks being part of salary for small startups that don't have actual money to pay you (or at least, that's what I've heard warnings for on HN).

Yep - your options trickle in over a vesting period.

Typically there’s also a ‘Cliff’ at the start - a period during which no options are available to you.

addendum: the ‘standard’ Silicon Valley stock option deal is: 4 year vest, 1 year cliff.

Eg: first 12 months, no options

Day 1 of 13th month - 25% of your options are available to you

Then the rest of the 3 years vest at a regular pace with the remaining 75% of your options dropping on a monthly cadence

The exception being Amazon who basically give you nothing for 2 years and then ramp up significantly.

Worth noting that Google and Facebook no longer have a cliff, and Google has also started experimenting with frontloading your initial vest (something like 40/30/20/10) to avoid the "dreaded" fifth year drop.

Yep you got it. Usually you vest 25% of your hiring offer per year, so after four years you’re fully vested. Some companies skew it towards later in the four year period to keep folks from jumping ship after the first payout (“golden handcuffs”). I’ve seen Amazon’s stock vesting schedule set at 5-15-40-40.

Big corps pay RSUs as part of your compensation package.

This helps them reduce compensation during hard times. Salaries are very sticky; it’s hard to cut salaries. So they offer RSU comp because it’s tied to stock price. When the company is doing poorly, they can pay less. But it also lets the pay high compensation and retain long term talent.

depends, for a public company like google when you get hired in addition to base salary you may get a yearly bonus and also RSUs which are free google shares, dispersed evenly over 4 years. When you get to year 1 at the company you get the first years shares(1 year vested) deposited in your brokerage account, and then they "vest" and are given to you on a quarterly cadence until the 4 years are up(if you are employed the entire time).

In addition to the initial grant at year 2 during your review some employees get more shares on top of the initial grant(that vest over a certain time frame, usually 2-4 years), these are called stacking RSU grants and its why people stay at FANG companies a long time as these grants stack higher and higher all the while your career progresses and the company stock goes higher.