Varistor help

[librian 1969]

Hi, could somebody please shed some information on varistors. What exactly do they do, why and where are they used and can they be tested, (in circuit and out of circuit)?? Thanks Librian 1969:

 

[CanonMan75]

Hi, could somebody please shed some information on varistors. What exactly do they do, why and where are they used and can they be tested, (in circuit and out of circuit)?? Thanks Librian 1969:

It took me all of five seconds to come up with this:

https://en.wikipedia.org/wiki/Varistor

Ever heard of Wikipedia or Google