Vibrators are probably the single most popular sex toy, mostly for women, but also for men. Like a dildo, a vibrator is designed to simulate the shape of an erect penis to a greater or lesser extent, with the addition of motor that makes it oscillate (or vibrate) back and forth slightly. 

Typically, the motor will be capable of varying speeds, with some vibrators even featuring more than one motor.    There is a wide variation in how true to life vibrators are in shape - and virtually no sex toy can match the vibrator for the sheer variety of colors they come in.

Most vibrators made from hard materials, such as plastics or metal, which are rigid in form, and often only vaguely resemble a penis in shape.  Some of them feature a two-pronged style, intended for simultaneous insertion in the vagina and anus, while others have a small extension that provides direct clitoral stimulation during vaginal penetration.  These two-pronged varieties are the type  most likely to feature multiple motors.

Because vibrators are only inspired by the shape of the male anatomy, not limited by it, there are some that are quite large – big vibrators that are bigger than the penises of all but the most notorious male porn stars.  While not for everyone, a big vibrator such as this can be an interesting change of pace – and it's much easier to find a vibrator of the appropriate size than an available man who's similarly well hung.

Still other vibrators are even more removed from  the original in design.  These include the double-headed vibrator, which is designed to be used by two women at the same time, and the strap on vibrator.  The strap on is designed to be worn by a woman, and comes with a specially designed belt that it is fitted to, enabling the woman to penetrate a man anally, or to penetrate a women either vaginally or anally.  There are even some vibrators that combine elements of the strap on vibrator with the doubled-headed vibrator, allowing the woman wearing the strap on to also enjoy penetration while penetrating another person.

Although some people confuse the two, or use the two words interchangeably, the line between dildos and vibrators is really quite simple: vibrators move under their own power, dildos do not.  That said, when using either a dildo or a vibrator, there is always time for lubricant.

After using a vibrator, it is important to clean it as soon as possible.  Different materials require different cleaning methods, but all the most common options are covered in this article about Sex Toy Cleaning Tips.  If you are engaged in sex play where the vibrator may be inserted into more than one orifice, or more than one person, it is a good idea to put a condom on the vibrator, and change it over each time you change the vibrator's use.  This is good safe sex practice, and also has the pleasant effect of making the vibrator easier to clean.