There are a number of different LaTeX packages and fonts that allow the symbol for the euro, the European currency unit, to be printed. The one I recommend below is the simplest and conforms best to the official rules.
One problem is that the official symbol is meant to be a sans serif character, always the same regardless of the font being used. This violates normal typesetting design and practice. After all, the dollar and pound signs are different for different fonts.
Of the various packages available, I recommend eurosans.
This creates the command \euro which is always sans serif, but changes to bold and/or italic as needed.
All this is hard to demonstrate in HTML (no euro symbol yet), but can be seen in the PDF version.
All the package and font files can be obtained from a local zipped file.