How does hike really work in startups?

It's that time of the year! Does it depend on how you performed in previous appraisal cycle? Does it depend who's most important to your manager? Or does it go by, crying baby airways gets the milk first? Or does it depend on budget allocated for your team? And finally who decides these numbers, is it your manager or someone much higher in the leadership like a CTO for engineering. A lot of these questions might seem very dumb to you, but I genuinely don't know how the system works