Conversation so far:
How many records has linkin park sold?
Linkin Park has sold more than 70 million records.
What was their best selling album?
The group's first studio album Hybrid Theory is one of the best-selling albums in the US.
When was Hybrid theory released?
CANNOTANSWER.

Question: what was Linkin Park's greatest achievement?
Self-contained rewrite: What was the group Linkin Park's greatest achievement?