不像冒號，分號主要分隔獨立的子句，以及分隔長句的主要成分。當句子的主要成分沒有連詞連線時，就要使用分號。注意：這些句子成分必須是獨立的子句，並且應該能夠獨立地傳達意思。

請看下面的例子:

Two-third of the Senate approved the finance bill. Others were against it.

在類似上述的句子中，作者經常犯使用逗號的錯誤。但是，在這個句子中插入逗號會導致“逗號拼接”錯誤。如果兩個句子之間是連詞，那麼可以使用一個逗號連線這個句子。

Two-third of the Senate approved the finance bill, but others were against it.

此外，當使用過渡短語或副詞將兩個獨立的句子連線在一起時，也需要使用分號。

I worked as an intern with the accounting firm across the street; however, I never truly learned much from the firm.

The President rarely attends policing matters; on the other hand, the sheriff is the right office for enforcing the law in some states.

當然，分號最常見的用法是用來分隔系列中的項。注意:分號只在專案包含內部標點符號時輸入。其他情況主要是逗號。

分號在強度上介於逗號和句號之間。一般來說，它更接近句號而不是逗號。分號主要在以下三種情況下使用：

連線兩個獨立的句子

我們可以用分號來分隔兩個主題或內容密切相關的句子：

(1) Come to my office tomorrow; I will have the document prepared.

(2) Few newly enrolled students know exactly what career path their studies will eventually offer; most find their area of interest during their studies.

在這種情況下第二句不以大寫字母開頭，除非它是一個總是以大寫字母開頭的單詞。

連線由連線副詞引導的分句

我們可以在連線詞前用分號。

可以使用分號的連線詞包括：

also, anyway, besides, consequently, furthermore, hence, however, incidentally, indeed, moreover, nevertheless, next, nonetheless, otherwise, similarly, still, then, therefore, and thus

具體例子如下：

(3) The deadline for the assignment is due tomorrow; therefore, additional study time has been scheduled.

(4) Exams are a means of measuring ability; however, not everyone performs well in them.

我們也可以在連線短語前使用分號。

下面的短語就有這樣的連線功能：

after all, as a matter of fact, as a result, at the same time, even so, for example, for instance, in addition, in conclusion, in fact, in other words, in the first place, of course, on the contrary, and on the other hand.

具體例子如下：

(5) Exams are a means of measuring ability; as a result, not everyone performs well in them.

(6) Critical thinking is essential at university; at the same time, it is difficult to teach.

連線由逗號分隔的成分

如果沒有分號，這些被逗號隔開的成分相互之間的關係就會很模糊，容易引起費解或誤解。如：

(7) There are many faculties at a university: Arts; Behavioural, Cognitive and Social Sciences; Humanities; Environmental and Rural Science; Science and Technology; Business, Economics and Public Policy; Law; Education; and Rural Medicine and Health.

有些參考文獻系統，如Harvard，在引用多個條目時使用分號分隔文字內引用。

(8) (Jones 2007; Johansson & Olofsson 1998; Strongman et al. 2003)

(9)On our vacation, we visited London, England; Paris, France; Berlin, Germany; and Rome, Italy.

上句話中的幾個地點因為也被逗號隔開，表明大小地方的從屬關係，所以如果沒有分號隔開，地點之間的關係也會較為模糊。