The Spanish currency is the Euro, although you might find that bartering with a sheep or cow gets you further. Spain is a very modern country with all the types of shops you might expect to find back home.
Clothes are often cheaper than you'll find in other European cities, while the huge department store El Corte Ingles will sell just about anything you ever wanted.
Whether you just want to buy a stamp or you plan on bringing a whole leg of The most likely thing you're going to want to buy: a stamp.
However, if all you are after is a stamp, it isn't worth waiting in line when there is a simpler (although slightly illogical) alternative - a tobacconist.
Tobacconist are called 'estancos' and have a burgundy and yellow sign. It is best to write on your postcard the destination country in both Spanish and English (see below for translations) - showing the postcard to the assistant and pointing to the name of the country will guarantee you get the correct postage.
Mailboxes in Spain are yellow and they can be found all over the city.
If you want to send an old-fashioned letter, envelopes and writing paper can be bought in a 'papeleria', or in El Corte Inglés (the big department store that can be found in every big city in Spain).
To avoid confusion, use this Spanish Post Price Calculator and then buy the exact quantity of stamps you need.
Useful Spanish If you have tried to buy acetaminophen in Spain and failed to come across it, that is because acetaminophen is the US-only name for the product. Paracetamol can be found in all pharmacies in Spain.Look out for the illuminated green cross outside buildings.Note that the Spanish tend to take higher doses of paracetamol than in most countries, with 1g (that's 1000mg! Ask for a lower dosage (200mg or 500mg should be available).Another common drug with a different name outside the US is albuterol, which is called salbutamol in most countries.Other drugs with different names in Spain compared to in the US are the following (the name in brackets is the American name): glibenclamide (glyburide), isoprenaline (isoproterenol), moracizine (moricizine), orciprenaline (metaproterenol), paracetamol (acetaminophen), pethidine (meperidine), rifampicin (rifampin), and torasemide (torsemide).I am genuinely surprised that people still go into banks to exchange money these days.