what ARE emulation handhelds, and WHICH one should I buy!?

if i told 8 year old me i could play tenkaichi 3 on the go i wouldve called you a LIAR!!!! 0:00 intro 0:28 what are emulation handhelds? 1:31 popular manufacturers 5:33 which one should I get? 8:03 do you own other consoles? 9:29 how do I use mine? 12:15 emulation, my beloved... 12:15 outro xoxo, @dejectedcatgirl