Explanation
The command "ip nat inside source list 1 interface gigabitethernet0/0 overload" translates all source addresses that pass access list 1, which means 172.16.1.0/24 subnet, into an address assigned to gigabitethernet0/0 interface. Overload keyword allows to map multiple IP addresses to a single registered IP address (many-toone) by using different ports so it is called Port Address Translation (PAT).

Explanation
MACsec, defined in 802.1AE, provides MAC-layer encryption over wired networks by using out-of-band methods for encryption keying. The MACsec Key Agreement (MKA) Protocol provides the required session keys and manages the required encryption keys. MKA and MACsec are implemented after successful authentication using the 802.1x Extensible Authentication Protocol (EAP-TLS) or Pre Shared Key (PSK) framework.
Reference:
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9300/software/release/16-9/configuration_guide/sec/

Ref: Scaling Networks v6 Companion Guide
"STP
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Extended System ID
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Bridge Priority
The bridge priority is a customizable value that can be used to influence which switch becomes the root bridge. The switch with the lowest priority, which implies the lowest BID, becomes the root bridge because a lower priority value takes precedence.
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The default priority value for all Cisco switches is the decimal value 32768. The range is 0 to 61440, in increments of 4096. Therefore, valid priority values are 0, 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056, 49152, 53248, 57344, and 61440. A bridge priority of 0 takes precedence over all other bridge priorities. All other values are rejected.

Explanation
On premise: customizable,specific requirements,resources
Cloud: scale, built-in automated backup, strong stable internet