"Quindi", "dunque" and "perciò" (and also "pertanto") are used to connect clauses when the last one is the logically consequence of the first. Like "therefore", as you wrote. They are called "congiunzioni conclusive", and you can use whichever you prefer. "Pertanto" is a bit more formal than the others. "Penso, dunque/quindi/perciò/pertanto sono" ("I think, therefore I am") "Quindi" can also assume the role that "then" plays in English: "Sono stato al supermercato, quindi sono tornato a casa" ("I went to the supermarket, then I came back home") "Dunque" is used in some expressions, like "venire al dunque" ("get to the point") "Comunque" is different. It has multiple meaning, but not the one above: 1) It can mean "whatever", "no matter what", "no matter how": "Comunque la pensiate, a me la pizza con l'ananas non piace" ("whatever you think about it, I don't like pizza with pineapple") 2) It can have adversative value, like "tuttavia", meaning "however", "nonetheless": "Non so se ce l'ho fatta, comunque ci ho provato" ("I don't know if I succeed, however, I tried") 3) It can mean "anyway": "Verrò comunque!" ("I'll come anyway") Hope it helps

{a) comunque, b) quindi, c) dunque, d) perciò} I) some examples: a1) Lo vedo che piove e fa freddo, devo comunque (anyway) andare. a2) Ho bisogno del mio tavolo da lavoro, comunque sia (by all means, anyway it might be)! b1) Tu conosci Carlo, Carlo conosce Antonio, quindi (therefore) possiamo riuscire a parlare con Antonio, bene! b2) (short dialogue) A) Dopo tante ore siamo riusciti a trovare la strada, ma era bloccata da un grande masso (pausing) B) Quindi ? (And ?) A) Abbiamo impiegato altre due ore per girare intorno al masso senza cadere dal precipizio. b3a) Usiamo adesso il lemma per dimostrare il teorema, b3b) dal lemma otteniamo: a+b=c (a e b entrambi positivi), quindi (it follows, therefore) c e` anche positvo, e il teorema e` dimostrato. Dunque (as a matter of fact, following what just happened), se non avete domande, (waiting a while ...) la lezione e` conclusa. Grazie, arrivederci. c1) Dunque (restarting a dialogue), ti stavo dicendo che Luca e Franca non verranno alla festa, quindi (as a result, therefore) possiamo invitare altre due persone. d1) Non mi piace andare sulla spiaggia, percio` (per questo, for this reason) quest'anno spero che andremo in montagna per le vacanze.

comunque = see Tano's examples. Let me just add that you should always think there is a verb after that: "comunque + sia" (anyway the things go), eg "comunque [# sia andata], ci ho provato (it doesn't matter how the things have gone, I have tried) quindi = hence, therefore, so dunque = then, right after that perciò = lit. "because of that", "as a consequence of that". Those above have more a slightly temporal "flavour", the latter is used as a cause-effect connection. Of course they create confusion! they all mean "as a logic consequence of the afore said fact", and they can be used as synonyms in long reasonments not to repeat always the same conjunction (quindi, quindi, quindi...). Please keep in account that the Italian language often builds (those treacherous) very long sentences; and the frequent subordinate clauses are then introduced by such types of conjunctions. Hence, I warmly suggest you to become acquainted with the Conjunctions and the Clauses that they introduce -- of course, the more of practice makes the most of theory. Best;