A digression is a stretch of talk or writing that leaves your main subject and goes somewhere else for a while. You have not changed the real topic; you have just stepped off the path.

A digression is離題指的是 a stretch of talk or writing一段話或一段文字， that leaves your main subject離開了你原本的主題 and goes somewhere else for a while暫時走去別的地方。You have not changed你並沒有換掉 the real topic真正的主題； you have just stepped off the path你只是暫時走出了那條路。

Teachers do this constantly: a story, a joke, a “by the way,” then “anyway, back to the point.” That return sentence is the sound of a digression ending.

Teachers do this constantly老師常常這樣做：a story, a joke, a "by the way,"說個故事、講個笑話、來一句「順便一提」， then "anyway, back to the point."然後說「總之，回到正題」。That return sentence那句拉回來的話 is the sound of a digression ending就是離題結束的聲音。

The word is a little bookish. In ordinary talk people say they went off topic, or that something was a side story.

The word這個字 is a little bookish有點書面。In ordinary talk平常說話， people say大家會說 they went off topic他們離題了， or that something was a side story或說什麼是一段題外話。

A short digression can warm a lesson; a long one makes listeners lose the thread. You can also use it sharply: calling something a digression means it does not belong here.

A short digression短短的離題 can warm a lesson可以讓一堂課更有溫度； a long one長長的離題 makes listeners lose the thread會讓聽的人抓不到重點。You can also use it sharply你也可以用得比較尖銳：calling something a digression說某件事是離題 means it does not belong here意思是它不該出現在這裡。