A euphemism is a generally innocuous word or expression used in place of one that may be found offensive or suggest something unpleasant. Some euphemisms are intended to amuse; while others use bland, inoffensive, and often misleading terms for things the user wishes to dissimulate or downplay. Euphemisms are used for dissimulation, to refer to taboo topics (such as disability, sex, excretion, and death) in a polite way, and to mask profanity. The opposite of euphemism roughly equates to dysphemism.
Euphemisms may be used to avoid words considered rude, while still conveying their meaning; words may be replaced by similar-sounding words, gentler words, or placeholders. Some euphemisms have become accepted in certain societies for uncomfortable information; for example, in the United States, a doctor is likely to say "the patient passed away" rather than "the patient died". They can be used to downplay or conceal unpalatable facts, such as "collateral damage" for "civilian casualties" in a military context, or "redacted" for "censored".
How often do you use euphemisms?
I don't usually use them. I will choose a more polite term if necessary, but I refuse to use words like poo. I could use something like pass away, but generally I'd favour die.