Hardware and Peripherals: Ports, Power, and Diagnostics
Core concepts
Know Apple's port and connector landscape: USB-C/Thunderbolt, MagSafe, Lightning (older devices), and how Thunderbolt differs from USB in bandwidth and daisy-chaining. Understand power adapters and wattage - a lower-wattage adapter charges slowly or not at all under load. Know battery health, cycle counts, and Optimized Battery Charging.
Understand Apple silicon vs. Intel Macs: unified memory, boot behavior, and Startup Security settings. Know Apple Diagnostics (hold power or press D on Intel), Disk Utility first aid, and Recovery modes. For peripherals, understand Bluetooth pairing/reset, AirDrop/Continuity requirements (same Apple ID, Bluetooth/Wi-Fi on), and Handoff. Know Target Disk Mode (Intel) vs. Mac Sharing Mode (Apple silicon).
Traps
Questions assume any USB-C cable supports Thunderbolt or full charging - many are charge-only or USB 2.0. Another trap: assuming a MacBook powers on from a low-wattage adapter (it may not). Don't confuse Apple Diagnostics with Recovery; they serve different purposes. Bluetooth issues are often resolved by removing and re-pairing, not just toggling.
Rule of thumb
Match the cable/adapter to the task: check for Thunderbolt/USB-C data rating and adequate wattage before blaming the device.
Worked example
A MacBook won't charge from a phone charger. The adapter's wattage is below the device's requirement - use the correct higher-wattage adapter.