A dissertation is a long piece of writing on one subject, written to earn a university degree. It is researched, argued, and much longer than a school essay. You live with one question for months or years and try to show you can answer it with evidence.

A dissertation A dissertation（學位論文） is a long piece of writing on one subject是針對一個主題所寫的長篇文章, written to earn a university degree寫來取得大學學位的。It它 is researched, argued經過研究、有論證, and than a school essay而且比學校的一篇作文 much longer長得多。You live with one question for months or years你會跟同一個問題相處好幾個月甚至好幾年, and try to show you can answer it with evidence試著用證據證明你能回答這個問題。

Though actually, British and American universities do not use the word the same way, and textbooks often hide that.

Though actually不過其實, British and American universities do not use the word the same way英國和美國的大學用這個字的方式不一樣, and textbooks often hide that而教科書常常沒有講清楚這一點。

In the United States, the big book for a PhD is usually a dissertation, and a master’s paper is often a thesis. In much of the UK and Europe, a dissertation is often the long paper for a master’s (sometimes even a bachelor’s), and the PhD book may be called a thesis.

In the United States在美國, the big book for a PhD is usually a dissertation博士的那本大部頭通常叫dissertation, and a master's paper is often a thesis而碩士的論文通常叫thesis。In much of the UK and Europe在英國和歐洲大部分地方, a dissertation is often the long paper for a master's dissertation通常是指碩士的長篇論文 (sometimes even a bachelor's)（有時候甚至是學士的）, and the PhD book may be called a thesis而博士的那本可能叫做thesis。

Always check what your own department means. Taiwanese students mostly say 論文 for both, and add 碩士 or 博士 when they need to be clear.

Always check what your own department means一定要確認自己系上是怎麼用這兩個字的。Taiwanese students mostly say 論文 for both台灣學生兩種通常都說「論文」, and add 碩士 or 博士 when they need to be clear需要講清楚時才加上「碩士」或「博士」。