What are the advantages of HTTP/2?

The primary advantage of HTTP/2 is its improved speed over HTTP/1.1. This is achieved thanks to a combination of elements:

HTTP/2 is binary, instead of textual meaning it is more compact, travels faster ‘on the wire’ and is less susceptible to errors.
HTTP/2 is fully multiplexed. This sees it send multiple requests between browsers and servers at the same time over a single TCP connection. This means faster page loading and a fairer spread of network resources because poorly-behaved applications won’t ‘steal’ TCP connections from well-behaved applications as they did using HTTP/1.1
It uses HPACK header compression to reduce overhead. Web page HTML headers are data-heavy and compressing them means they can be sent between browser and server in one trip, over one TCP connection.
It allows servers to ‘push’ responses proactively into browser caches instead of waiting for a new request for each resource. To do this the server ‘speculatively’ sends data which it anticipates the browser needing.
HTTP/2 incorporates the new ALPN extension allowing for faster-encrypted connections and decreased load times because the application protocol is determined during the initial connection.
HTTP/2 reduces additional round-trip times (RTT), meaning websites load faster with less optimisation.
Workarounds like asset concatenation and domain sharding aren’t needed with HTTP/2.