Bitcoin Script enables the creation of Bitcoin wallets, with conditional logic for spending.
One of the most common uses is a 2 of 3
multisig wallet (Multiple Signatures).
To spend funds from such a wallet, 2 of the 3 participants are required to sign off.
It is flexible, you can adjust the number of participants, threshold parameters, and
add conditional logic (i.e. this AND that; this OR that).
It also let's you use time conditions (timelocks) for spending (e.g. can spend after a certain date).