Subordinate conjunctions join two clauses forming a relationship of dependence. The subordinate clause depends on the main clause for complete sense. In Italian, the subordinate clause often has a conjugated verb that completes or specifies the information of the main clause.

The main categories are causal, temporal, final, consecutive, concessive, and completive. Each category expresses a different type of logical relationship between the two clauses. Recognizing the category helps you choose the correct conjunction and predict the structure of the subordinate clause.

Causal conjunctions introduce the reason or cause and usually use "because" or "since". In formal written language, "since" is also common, and less often "as". The causal subordinate clause can precede or follow the main clause without changing the logical relation.

Temporal conjunctions place an event in time relative to the main clause. The most common conjunctions are "when", "while", and "before". "Before" often requires the subjunctive because it introduces an event not yet realized.

Final clauses express purpose and in Italian mainly use "affinché" and "perché". In the final sense, "perché" is normally constructed with the subjunctive. The final subordinate clause indicates the intention or end of what is said in the main clause.

Consecutive clauses express a consequence and are often built with "così che" or the structure "tanto... che". The subordinate clause may require the subjunctive or the indicative depending on nuance and structure. In implicit consecutives, an infinitive with "to the point of" can be found.

Concessive clauses admit a fact that does not prevent what is stated in the main clause. The most common forms are "benché", "sebbene" and "nonostante". "Benché" and "sebbene" normally take the subjunctive.

Completives introduced by "that" complete a verb, a noun, or an adjective of the main clause. In many completives, the indicative and subjunctive alternate depending on the meaning, not the presence of "that". The "object completive" is the most frequent type and answers the question "what".

Many subordinate clauses use the subjunctive when expressing will, doubt, subjective opinion or anticipated anteriority. The indicative is preferred with facts considered certain or presented as reality. The same conjunction can require different tenses depending on the sense and the category.

Some conjunctions are more formal or typical of written language, such as "poiché" and "giacché". In speech, "perché" predominates for the causal value. The choice influences the tone of the text but does not change the type of subordination.

Subordinate conjunctions connect clauses creating dependence and a choice of structure. Different categories express cause, time, purpose, consequence, concession, and completion. Mastery comes from recognizing the logical relationship and applying the appropriate conjugation in the subordinate clause.