届く

1. Origins, structure, and basic meaning

• Structure: 届く(とどく) is an intransitive verb for an item arriving or for a hand, sound, or similar thing reaching a point.
• Basic usage: The arriving item takes が in 荷物が届く, as does the reaching subject in 手が棚まで届く.

2. Common pitfalls and similar expressions

• Arrival and reach
  • Read it as “arrive” for a delivery and as “reach” when a hand extends to a shelf.
• Difference from 届ける
  • 届く is intransitive and describes arrival, while 届ける is transitive and describes someone delivering an item.