That'll be discussed in Chapter 5 but the short answer is control over bits.

nitter.moomoo.me/McPlebovic/status/1646464405385691138#m (https://nitter.moomoo.me/McPlebovic/status/1646464405385691138#m)

https://nitter.moomoo.me/JasonPLowery/status/1646466819220287489#m