Words, words...

So what is "21st century socialism"?  This is the phrase used by Jeremy Corbyn in his key-note speech on the final day of the Labour Party's annual conference.  Rather like "brexit means brexit" it's a somewhat meaningless phrase - or rather, it's one of those useful pronouncements which can mean whatever you want it to mean.  But why add 21st century? Is this something different from (pre-21st century) socialism? Bit like Blair changing Labour to New Labour which didn't really change anything?