Bitcoin Script

Quick refs: opcodes.md, output-types.md, tapscript.md

Bitcoin Script is a stack-based, non-Turing-complete (no loops), forth-like language. Each opcode pushes/pops bytes from a stack. Validity = stack contains a single non-zero element after execution.

Execution model

1. Initialize empty stack.
2. Concatenate scriptSig + scriptPubKey (legacy) — execute serialized. (Disabled post-BIP16 P2SH for the segwit/taproot path.)
3. (For SegWit/Taproot) Witness stack pushes are pre-loaded onto the stack, then scriptPubKey (or witness script) executes.
4. After execution: top of stack must be non-zero / true.

Output type catalogue