Formal stationery is sophisticated and understated usually adorned with a name or small monogram.  Whether you are responding to a social invitation, sending a wedding thank you or acknowledging the death of a loved one; a classic folded note or correspondence card is what you need.

Choose your stationery based on to whom you are writing and the purpose of your correspondence.  Line the envelope for added elegance and save time on writing your return address by having it engraved or printed in thermography.