電(dian)(dian)(dian)阻(zu)(zu)器是限制電(dian)(dian)(dian)流(liu)的元件，通常簡稱為電(dian)(dian)(dian)阻(zu)(zu)，是一種最常用(yong)(yong)的電(dian)(dian)(dian)子元件，普遍應用(yong)(yong)在各類電(dian)(dian)(dian)子電(dian)(dian)(dian)路中。不但金屬(shu)導體(ti)有(you)(you)電(dian)(dian)(dian)阻(zu)(zu)，其(qi)他物體(ti)也(ye)有(you)(you)電(dian)(dian)(dian)阻(zu)(zu)。

簡(jian)單來說，電(dian)(dian)阻(zu)(zu)就(jiu)是(shi)指(zhi)電(dian)(dian)流(liu)在(zai)電(dian)(dian)路中所遇到的阻(zu)(zu)力，或者說是(shi)指(zhi)物體對電(dian)(dian)流(liu)的阻(zu)(zu)礙才能。電(dian)(dian)阻(zu)(zu)越(yue)(yue)大(da)，電(dian)(dian)流(liu)所遭到的阻(zu)(zu)力就(jiu)越(yue)(yue)大(da)，因(yin)(yin)而(er)電(dian)(dian)流(liu)就(jiu)越(yue)(yue)小(xiao)(xiao)。反(fan)之(zhi)，電(dian)(dian)阻(zu)(zu)越(yue)(yue)小(xiao)(xiao)，電(dian)(dian)流(liu)所遭到的阻(zu)(zu)力就(jiu)越(yue)(yue)小(xiao)(xiao)，因(yin)(yin)而(er)電(dian)(dian)流(liu)就(jiu)越(yue)(yue)大(da)。

電(dian)阻(zu)的符號(hao)是“R”。電(dian)阻(zu)的單位(wei)為(wei)歐(ou)姆(mu)，簡稱(cheng)歐(ou)，用字母“Ω”表示。常用的電(dian)阻(zu)單位(wei)還有千(qian)歐(ou)姆(mu)（KΩ），兆(zhao)歐(ou)姆(mu)（MΩ）。