What is meant by a 'global economic meltdown'?

To be honest I'm 16 and not very literate in economics, so I don't fully understand the concept. <br>Every time I hear about us potentially sliding into recession there is talk about the economy imploding and the current global systems that support globalisation like trade and finance melting down.<br>How likely would that actually be?<br>What are the consequences of that occurring, would it be a full scale collapse or just that the global economy was hard hit.