It's vital to note that most entertainment overlaps more than one category here ...
... and just as important to note that, when it's the primary, Porn is the one that needs to overlap the least. Porn is not just the naked people and their various insertions (CAREFUL WITH THAT AX, EUGENE), it's any entertainment that you seek out to animalistically fill a specific need. It's not about quality or enlightenment, it's about hole-filling.
Sex Porn is the traditional example (Y'ALL DURN PREVERTS AND YUR SEX PORN), but anything can be pornified if you have some huge need to look at it. There's architecture porn and real estate porn and food porn and abandoned building porn and emotion porn, and I think sports IS sports porn but we just call it sports. Porn is when you need to stare at something purely because of what it is. There's no subtext -- there's just that preprogrammed Thing You Like, and you want as much of it as possible until you're so inured to it that the only way you can get off is having it presented to you by vomiting amputees in underwater vacuum beds. Porn is about MORE, on a primal level, and there's probably more of it than anything else. Earth itself is probably just species porn, come to think of it. Hot.
Subcategory: The Surrogate
This is when a more substantial need is unfulfilled in real life and thus you must get it from entertainment instead -- not in a pejorative sense, just in the sense that people need things (EXCEPT FOR BONO, WE DON'T NEED HIM). Porn instead of sex, TV instead of parents, MMORPGs instead of friends, music that accepts you when nobody else will, stories that give you hope because ain't no hope. Humor websites instead of doing your homework doesn't count, though, so stop reading this before you end up writing Internet humor instead of having a life.
In the same way that when we say we like movies we mean we like GREAT movies, this list is basically an excuse to talk about the Beautiful. It's just that -- the more otherworldly stuff that gives you goosebumps and in the moment actively makes things right. I can convey exactly why I like RoboCop, but if you ask why I like my favorite songs, I just stammer moronically because music is the art form that absolutely owns the Beautiful and it's the category that's hardest to describe. I'll try, though, and although I could do it with videos of stirring piano solos or that flash mob that relentlessly plays "Ode to Joy" until you collapse in a blubbering heap, I'll instead go with ... a Jackson 5 song.
It's "I Want You Back," and in this video right here it's about to be performed by singer-songwriter KT Tunstall on some kind of Gallic music show. Tunstall's all about the live looping (accompanying herself by recording bits of audio live and playing them back as she goes), and as the video starts the lights go down and she starts laying down a percussion loop by tapping on the body of her guitar. Oh, except she completely fucks it up, and the whole thing crashes to a halt after about 10 seconds and suddenly it's the opposite of beautiful -- it's that feeling of being mortified for someone else as they blow it IN FRONT OF EVERYONE and the house lights come up and there's some Pity Applause and the host is saying something in French and he sounds annoyed and YOU SUCK TUNSTALL THIS IS EASILY THE WORST VIDEO EVER. But this is what makes it so perfect.
Because the lights then go back down and she gets it right this time, and then she starts in with the opening chords and everyone who hadn't recognized the song from the title starts cheering, and that builds, more people are recognizing what song it is, and then she starts singing and now everyone knows what song it is and everyone likes that fuckin' song, and holy shit their expectations were low a second ago but here are the vocals and they're incredible, it's a goddamn Quality Ambush, and there's something particularly beautiful about a cover song because when it's good, it's beauty on top of itself, it's like when a tyrannical father in the '60s literally whips his children into performing pop songs and it's evil as fuck but thanks only to those kids some beauty at least escaped all that bullshit, and then 40 years later a few hundred French people are sitting in a darkened room watching some Scottish chick they've never heard of doing a solo version of one of those songs and it's a beautiful version of a beautiful song, and it's beautiful how she's using looping to accompany herself because it's unusual and tricky and she sounds like four people, and it's beautiful how unmistakably genuine and reflexive the roar of applause is when she finishes, and it's beautiful that a song can sort of exist outside of time as its own entity of shared experience and through musicians we tap into it and get a lump in our throat without even knowing why, and it's beautiful that for the duration of the song you can't think about anything else, everything is right, you forget there's tyranny in the world, you forget there are categories, and you stop caring forever that the performance started with her fucking up and the house lights coming on and everyone being embarrassed for her. Because that's in the past now. But that song will still be making things right another 40 years from now, and our need for such distractions brings us together, and that's why entertainment is a beautiful thing.