Dildos 

A dildo is a sexual aid, or sex toy, which can be used on both men and women. It is generally a penis shaped device, used for penetration of the butt, vagina or mouth. It can be used during both Masturbation and Sexual Intercourse. People sometimes call them "Dills" and my favorite history of the name (no idea if this is true) is: it comes from Italian word "diletto" which means delight.  But the main thing that separates a dildo from vibrators is...no motor and it just plain doesn't vibrate. 

Below is your guide to dildos. 

Types of Dildo's --Materials

A dildo can be made out of many different materials. Common materials are:

PVC- Pvc is the least expensive of the materials, however they are known to have a plasticy aroma and are porous so can harbour bacteria. It's usually fairly soft and flexible. And it also can be discolored fairly easily.  Since it is the cheapest material you will find the biggest dildo made out of pvc.

Silicone Rubber - Silicone Rubber is more expensive generally than their pvc cousins, but are much easier to keep clean as you can just boil them in water to sterilize. Another plus for silicone rubber dildo's is that they do not smell like plastic.  But they can disintegrate if you use silicon based lube. 

Chrome-plated Steel dildos - chrome and metal dildos are much more expensive than both rubber and pvc, however they provide a different set of sensations when inserted in the body. Many Dom's and mistresses in bdsm circles enjoy using this type of dildo for the very reason that it causes their play partner a slight discomfort. They do not flex like rubber or pvc dildo's; this can lead to an uncomfortable feeling. They also transfer heat really well so can provide interesting sensations when placed in the freezer. Easy to clean and sterilize and virtually indestructible. But expensive.

Pyrex glass- Pyrex glass is also an expensive material in comparison to silicon rubber and pvc. This type of dildo also doesn't flex when inserted into the body. The Pyrex glass dildo can be heated using warm water to body temperature and is easily sterilized with boiling water. Also, glass dildos heat up when inserted into the body and can feel comfortable once it has warmed to body temperature. These are great but don't drop them or they can shatter. Also, never bother with cheaper glass dildos which are much more likely to break and considering where they may be when they break...just use the pyrex ones.

Types of Dildo's -Variation in Shapes

The Double Dildo

The Double Dildo. Used for penetrating 2 females at the same time. Used frequently by bi girls and lesbians. Double sided dildo's are commonly used in lesbian sexual intercourse or in a group sex environment. They are also used in heterosexual intercourse for male anal penetration in a practice that is sometimes referred to as pegging. 

Non-Penis Shaped

Of course, not all dildos have to be penis shaped. Certain lesbians really dislike the whole penis shape thing and go for phallic shapes that are not penis-related. Say a banana shaped or ones that are shaped like cute teddy bears. Additionally, certain Asian countries have laws/difficulties with fake penis shaped objects but no problem with other extremely similar shapes...and that, coupled with 'Asian sensibilities' results in some rather odd incarnations of the dildo.

They can also be found in unconventional shapes that are more pleasure based in origin.

Strap-Ons

Strapons are harnesses made for holding dildos in place --just where a cock would normally go. This allows for women to fuck each other effectively. Or can be used as a humiliation play on males. This also works for those that do not want to or cannot use their actual penis.  Dildo require a good base and/or balls in order to be effective in a strap on harness.

Other Uses

Dildo's have many different uses. They can be used as a solo or mutual masturbation tool, of course.  They work as a sexual aid during sex both for men and women. If they are appropriately sized a phallic gag. They can also be used for artificial fellatio or for fellatio training. Larger dildo's can be used for intimidation and humiliation play. Flacid ones can be used by trans people to be placed in their underwear.

Health and Safety Issues facing use of dildos

 Sterilization of a dildo's is very important as Std's and common infection bacteria can be carried on a dildo and transferred to the person receiving insertion of the dildo. Common practice for a dildo being used by more than one person is too apply a condom over the dildo. Special care needs to be taken when using a dildo for anal insertion as they can be difficult to retrieve if it goes fully inside the anus. If a dildo should become fully lost inside someone’s anus, it is important to retrieve it – and this may require medical assistance. If the didos becomes lost and works its way up to the bladder area, a could cause a rupture and this means you’ll have to use a colostomy bag for the rest of your life. So swallow your pride and go to the emergency. To prevent a dildo from being swallowed completely by your ass, you can use a butt plug which has a large end to prevent total insertion.