Minecraft comes packed with simple graphics, but if you want to add a little visual flair to your world, modders have you covered. Here's a guide to installing fantastic Minecraft shaders.
Be forewarned, most shaderpacks are taxing on your hardware, and some players report a significant FPS hit even with top-of-the-line machines. There are "lite" versions of a lot of shaderpacks that I'll list below, but even those can be a rough on older video cards or computers without a lot of processing power. Still, if you have the cycles and you're looking to upgrade your experience, shaderpacks are there for you.
Step One: Get Yourself Some Forge
There are, theoretically, other ways to go about this, but right now the Forge API is the best way to install mods quickly and painlessly, so unless you're a whiz already (in which case you probably don't need this article), just download and run the Forge .jar and get on with your life (make sure to select the "forge" profile from your Minecraft launcher when you next start it up).
The next step is downloading and installing Optifine -- just drop the Optifine .jar in the "mods" folder wherever your Minecraft folder is. This is a terrific all-around visual upgrade that allows you to tinker with the graphics settings of Minecraft down to an incredibly granular degree. (By the way, if you're just looking for a general visual upgrade or some polish, you can stop here, but if you've come this far, why not reach a little further?) Among other things, installing Optifine will give you access to shaders, and even comes with some pre-installed, though you probably want to try out a few options to see what's a good fit for you.
All you need to do to open up your horizons is download the appropriate shaderpack (it will come in .zip form) and drop it in your "shaderpacks" folder. Here are some options for shaderpacks, though there are plenty more:
Let's talk specifics, shall we?
Sonic Ether's Unbelievable Shaders
Sonic Ether's Unbelievable Shaders -- or SEUS for short -- are some of the best shaders around, a god-tier collection of lighting and graphical upgrades that will essentially make Minecraft into a different game.
It is also one of the most resource-intensive shaderpacks out there, so don't try to install and run SEUS without enough horsepower or you're bound to end up with a very pretty slideshow. Still, if you're the kind of person who has a monster PC but is wasting its potential on vanilla Minecraft, this is your opportunity to shine.
KUDA shaders is another high-end shaderpack, but it's one that I (and others) have had a little better luck running without slowing performance to a crawl. However, like everything else with modded Minecraft, you will probably have to experiment a bit to find out what works for you. KUDA adds shadows, lighting, godrays and other fun visual tweaks to make your world come alive and, at its highest settings, is almost cinematic in quality.
Slidur's Vibrant Shaders and Chocapic13
These aren't the same shaderpack, but I've grouped them together because both of these are a lot easier to use if you're trying to tailor your experience to meet your hardware specifications. Both Slidur's and Chocapic13 come with options ranging from "lite" to "extreme", depending on how much you think your system can handle. Don't be fooled -- the "lite" option is still a pretty impressive visual upgrade, and they will still chug your machine if you're not careful. I have a relatively up-to-date rig, but by no means an impressive one, and I've had a lot more luck with these two shaderpacks than any others. If you're worried about frying your videocard, start with the lite versions of these and move up.
CrankerMan's TME Shaders
Another great shaderpack, if you have a machine that can handle it, is CrankerMan's TME Shaders -- to be clear, TME stands for "too many effects", so if you're looking for a light or processor-friendly shaderpack, this ain't it. For the bold though, it can be a real visual treat.
CaptTatsu's BSL Shaders
Also a high-performance choice, CaptTatsu's BSL shaders adds a few extra effects on top of the usual shader package, including some tweaks that make this especially good for caverns and indoor spaces.
Consider this Shaders 101 -- if you choose, you can tinker with the advanced mod options to fine-tune your experience to an extreme degree. If you have a favourite pack, a tip or there's something I missed, sound off in the comments and let us know!