Linked List

Like a scavenger hunt: each clue tells you where to find the next clue. Lose one, and you lose everything after it.

head
 │
 ▼
┌────┐     ┌────┐     ┌────┐
│ 10 │──→  │ 20 │──→  │ 30 │──→ NULL
└────┘     └────┘     └────┘

Cheap to insert at the head. Expensive to jump to the middle — you have to walk from the start.