電(dian)(dian)(dian)(dian)(dian)阻(zu)器是限制電(dian)(dian)(dian)(dian)(dian)流的元件(jian)，通常簡稱為電(dian)(dian)(dian)(dian)(dian)阻(zu)，是一種最常用(yong)的電(dian)(dian)(dian)(dian)(dian)子元件(jian)，普遍應用(yong)在(zai)各類電(dian)(dian)(dian)(dian)(dian)子電(dian)(dian)(dian)(dian)(dian)路中。不但金屬導體(ti)(ti)有電(dian)(dian)(dian)(dian)(dian)阻(zu)，其(qi)他物體(ti)(ti)也有電(dian)(dian)(dian)(dian)(dian)阻(zu)。

簡單來(lai)說，電(dian)(dian)阻(zu)(zu)(zu)就(jiu)是指(zhi)(zhi)電(dian)(dian)流(liu)在電(dian)(dian)路中(zhong)所遇到的阻(zu)(zu)(zu)力(li)，或者說是指(zhi)(zhi)物體對電(dian)(dian)流(liu)的阻(zu)(zu)(zu)礙才能。電(dian)(dian)阻(zu)(zu)(zu)越(yue)(yue)大，電(dian)(dian)流(liu)所遭(zao)到的阻(zu)(zu)(zu)力(li)就(jiu)越(yue)(yue)大，因(yin)而(er)電(dian)(dian)流(liu)就(jiu)越(yue)(yue)小。反之(zhi)，電(dian)(dian)阻(zu)(zu)(zu)越(yue)(yue)小，電(dian)(dian)流(liu)所遭(zao)到的阻(zu)(zu)(zu)力(li)就(jiu)越(yue)(yue)小，因(yin)而(er)電(dian)(dian)流(liu)就(jiu)越(yue)(yue)大。

電(dian)阻的符號是(shi)“R”。電(dian)阻的單(dan)位為歐(ou)姆，簡(jian)稱(cheng)歐(ou)，用字母“Ω”表(biao)示。常(chang)用的電(dian)阻單(dan)位還有千歐(ou)姆（KΩ），兆歐(ou)姆（MΩ）。