While on the surface it appears that a 0% unemployment rate would be terrific for the citizens of a country, having a small amount of unemployment is actually desirable.

　　从表面上看，零失业率对一个国家的公民来说应该是好到爆了，然而实际上保留一个小幅的失业率才是好事。

　　To understand why we need to look at the three types (or causes) of unemployment.

　　要弄明白为什么，我们首先得来看看失业的三种形式。(或者说三种成因)

　　Cyclical Unemployment is defined as occurring "when the unemployment rate moves in the opposite direction as the GDP growth rate. So when GDP growth is small (or negative) unemployment is high." When the economy goes into recession and workers are laid off, we have cyclical unemployment.

　　周期性失业的定义是：失业率与GDP的增速呈负相关的关系。也就是说，当GDP增长率很小(或者为负)的时候，失业率会很高。当一个经济体进入衰退期，工人开始失业的时候，我们就遭遇了周期性失业。

　　Cyclical unemployment occurs when an economy's output deviates from potential GDP- i.e. the long-term trend level of output in an economy.

　　当一个经济体的产出偏离潜在GDP的时候，也就是偏离长期的产出趋势的时候，周期性失业就出现了。

　　When an economy's output is higher than the level of potential GDP, resources are utilized at levels higher than normal and cyclical unemployment is negative.

　　而当经济体的产出比潜在GDP更高的时候，资源的利用率会比正常情况下更高，这时周期性失业率就会为负。

　　Conversely, when an economy's output is lower than the level of potential GDP, resources are utilized at levels lower than normal and cyclical unemployment is positive.

　　反过来，如果经济体的产出低于潜在GDP，资源的利用效率就会低于正常值，那周期性失业率就会为正。

　　Put simply, cyclical unemployment is unemployment associated with business cycles- i.e. recessions and booms.

　　简单地讲，周期性失业是和经济周期有关的失业，也就是衰退期和繁荣期。

　　Frictional Unemployment: We define frictional unemployment as "unemployment that comes from people moving between jobs, careers, and locations."

　　摩擦性失业：我们对摩擦性失业的定义是“当人们切换工作、行业或工作地点时发生的失业”。

　　If a person quits his job as an economics researcher to try and find a job in the music industry, we would consider this to be frictional unemployment.

　　如果一个人辞掉了经济学研究员的工作，转而去音乐行业找工作，就属于我们所说的摩擦性失业。

　　Frictional unemployment is unemployment that comes from people moving between jobs, careers, and locations- in other words, unemployment that arises because most people don't enter into a new job immediately after exiting an old one (voluntarily or involuntarily).

　　摩擦性失业会在人们切换工作、切换行业、切换工作地点的时候发生，换句话说，它的出现是因为人们辞掉旧工作之后并不能立刻开始一个新工作。(不管是自愿的还是非自愿的)

　　Frictional unemployment is not thought to be a big problem from a policy standpoint because it is entirely reasonable that people would take some time to find a job that is a good match rather than take the first opportunity that comes along.

　　从政策的角度来讲，摩擦性失业并不是一个大问题，因为它的成因完全可以理解，人们肯定更倾向于花点时间找个真正适合自己的工作，而不是单纯接受眼前的第一个机会。

　　Technology that helps to match workers with jobs and streamline the interview and hiring process most likely result in the amount of frictional unemployment that exists in an economy.

　　那些帮助求职者匹配新工作的技术，以及帮助他们优化面试和招聘流程的技术，很可能导致了一个经济体中摩擦性失业率的升高。

　　Structural Unemployment: We define structural unemployment as "unemployment that comes from there being an absence of demand for the workers that are available".

　　结构性失业：我们对结构性失业的定义是“当劳动力需求相较于现有求职者人数而言出现缺口时产生的失业。”

　　Structural unemployment is often due to technological change.