Why do we forget? Name the two main mechanisms.

Decay (traces fade with time) and interference (competing memories crowd each other out) — and sometimes the memory is still there but unreachable.

Forgetting isn't a single process:

• Decay — a memory trace weakens simply as time passes without use.
• Interference — other, similar memories compete and block access (learning a new phone number can smother the old one).

Crucially, forgetting is often retrieval failure, not erasure. The information may still be stored but temporarily inaccessible — which is why a forgotten name can suddenly resurface with the right cue. This distinction is the seed of the storage-vs-retrieval idea below.