Tapeout
Beginner
The moment the finished chip design file is sent to the factory to be made.
Novice
The release of the finished, fully checked layout file to the foundry, which uses it to make the masks for manufacturing. The name comes from the reels of magnetic tape that once carried the file.
Expert
A freeze as much as a technical step: one final layout file with a recorded checksum, the exact versions of the rule files, libraries and IP it was checked with, and a signed checklist. Any change after it means new masks.