These pronouns are used after a preposition or verb, often for greater emphasis (hence the name "stressed pronouns"). First we'll learn what these pronouns are, then we'll see how to use them.

So they look like a hybrid of direct or indirect object pronouns and subject pronouns. But take note: although Lei, lui, lei, noi, voi and loro look like subject pronouns, when used disjunctively they are not subjects!

So how are they used?

1) after a preposition

Questo libro è per te. (This book is for you.)
Siamo usciti con loro. (We went out with them.)
Pensa sempre a sé. (He always thinks about himself.)
Studiano sempre da sé. (They always study by themselves.)
A me non piace questo vino. (I don't like this wine - a more emphatic way of saying, "Non mi piace questo vino.")
Andiamo da lui. (We're going to his place.)

2) after a verb to give the direct or indirect object greater emphasis

Lo amo. - Amo lui. (I love him.)
Ti cercavo. - Cercavo te. (I was looking for you.)
Mi abbraccia. - Abbraccia me. (She hugs me.)

The above pairs of sentences have the same meanings, but the second in each pair is more emphatic. For even greater emphasis, use anche, proprio or solamente - e.g. Cercavo proprio te. Abbraccia solamente me.

3) after a verb to distinguish between multiple objects

Riconosce me ma non lui. - He recognizes me but not him.
Ha invitato noi e loro. - He invited us and them.

4) in comparisons

Marcello è più alto di me. (Marcello is taller than me.)
Loro sono meno paurosi di noi. (They are less fearful than us.)
Tuo fratello non era intelligente quanto te. (Your brother wasn't as smart as you.) 

A very common Italian idiomatic expression that uses stressed pronouns is, "Tocca a me!" - It's my turn! Of course, you can use it with the other disjunctive pronouns too - Tocca a te, tocca a noi, etc. So when the waiter brings you the bill and someone asks, "Chi paga oggi?" just say, "Eh purtroppo oggi tocca a te!" (Who's buying today? - Unfortunately today it's your turn!) C4N!