if something is broadcast live, it is broadcast on television or radio as it is actually happening [↪ prerecorded]:
The ceremony will be broadcast live on television.
The match will be shown live by the BBC.
if people perform live, they perform in front of people who have come to watch, rather than for a film, record etc:
I love their music, but I've never seen them perform live.
The band is playing live in Birmingham tonight.
Their latest CD was recorded live (=recorded at a live performance) in New York.
when a system or project goes live, people start to use it after it has been planned and discussed for a long time:
Their new information retrieval system went live last month.
a new security project which will go live in October