HTTP/2 enables a more efficient use of network
resources and a reduced perception of latency by introducing header
field compression and allowing multiple concurrent exchanges on the
same connection. It also introduces unsolicited push of
representations from servers to clients.

At a high level, HTTP/2:

is binary, instead of textual
is fully multiplexed, instead of ordered and blocking
can therefore use one connection for parallelism
uses header compression to reduce overhead
allows servers to “push” responses proactively into client caches

HTTP/2 is getting more and more attraction recently, so it is expected to have it in place in a larger number of websites we visit every day.

mod_http2/mod_proxy_http2 is supported with apache 2.4 but looks like it is experimental. Apache 2.5 will have the full support of it.