I have purchased 3 rib eye steaks. What is expiration?

If they were fresh when you bought them, cooking them 3 days after should be fine.

You can pretty much keep it until it smells bad, and when it does smell bad, just cut off the outside and the inside is still good. An aged steak is pretty common. If that's not the kind of work you want to put into it, just freeze it. It'll last virtually forever.

As for the darkening, that just the fluids dripping to the outside, the same thing happens with cut fruits. 

After steak is purchased, it may be refrigerated for 3 to 5 days - the "sell-by" date on the package may expire during that storage period, but the steak will remain safe to use after the sell by date if it has been properly stored.

Yes they are safe to eat.  The juices are just falling to the bottom part of the steak. If they smell ok, they are good.

Lots of fine restaurants don't cook steaks until they are green with mold. They scrape it off and then cook them up.  Truth

More expensive beef is aged for at least 28 days . Posh restaurants have been experimenting with beef aged for up to a year, so I think you can safely keep it in the fridge for a week or more.

They will be fine for three days. The only reasons they are getting dark is because 

A) Oxidation

B) The blood is leaching down to the underside of the steak due to gravity. If you turn the steak over you will see that it is very red and probably will be bloody.

Neither of these things will hurt a steak. 

If you bought them and want to extend the usage, freeze them. Freezing means they can be kept indefinitely, but keep in mind, they will get freezer burn, which does not harm them but can give them a rather funky taste, depending on your freezer.

They will brown when exposed to air. Sniff test. Smells bad? Toss them out. 

Store in the bottom of your fridge wrapped in glad wrap. Red meat is fine for 4 or 5 days in the fridge but if it smells off after 2, then it's not. Be careful with chicken, it doesn't last as well as red meat in the fridge.

First - there is NO EXPIRATION DATE! They're good until they are not, the darkening is just aging (oxidation mostly). My uncle (a butcher for a large grocery chain) used to buy the older meat that was marked down and brown because it was better eating due to longer aging. 

They are fine.. but I myself make sure I use meat within 4 days, tops. If you can't eat them now, cook them up and freeze. Even if you just cook them now, they would be good in the fridge for a few more days.