Big thanks to all who responded! I want to know the role that bitcoin scripts play in bitcoin transaction output. In other words, assume there are no scripts in bitcoin's transaction output and only a public key is there, what exactly will be impossible under this assumption? My question came from the following line in a textbook on Bitcoins: "...we study the Bitcoin scripting language and come to understand why a script is used [...in transaction's output...] instead of simply assigning a public key". But the book does a poor job in explaining it. That's why I'm asking it here. Thanks is advance for your patience with newbies :-)