Examples of enclitics occur in Latin, which has an interrogative particle -ne, and a conjunctive particle -que, amongst others.
Caesar puellam amat Caesar loves the girl.
Amatne Caesar puellam? Does Caesar love the girl?
Caesarne filiam amat? Is it Caesar who loves the girl?
Nonne Caesar filiam amat? Doesn't Caesar love the girl?
virginibus puerisque for girls and boys (pueris = for boys) - quote from Horace, also the title of a book by Robert Louis Stevenson
The Latin -que comes from an ancestral Proto-Indo-European *-kwe, as do the corresponding Greek enclitic -te and Sanskrit -ca. There is also a separate word for 'and', Latin et and Greek kai, which is not enclitic.
In Greek the possessive pronouns are also enclitic. We can regard the English possessive 's as enclitic too, because although it isn't pronounceable as a separate word, it behaves syntactically like one: the Queen of England's hair is the Queen's hair.
An enclitic follows the main word. A similar unstressed particle that precedes is called a proclitic. The general term for enclitics and proclitics is clitic.