An important caveat is that Bitcoin Script isn't enabled in the current implementation of Bitcoin, for obvious security reasons. The immense possibility of Script is yet another reason I am long on Bitcoin.
"This is a list of all Script words (commands/functions). Some of the more complicated opcodes are disabled out of concern that the client might have a bug in their implementation; if a transaction using such an opcode were to be included in the chain any fix would risk forking the chain."
Common wallet software just uses templates to create and decide which scripts are relevant to them— but the network itself absolutely does validate them.