Grout is a cement-based mixture. The basic ingredients in grout are Portland cement, sand, and water, once mixed together a chemical hardening process begins. It will even harden underwater. It does not dry. It is a chemical process that cures.
Grout has little adhesive properties and cannot be used to "stick" tiles in place.
It is dangerous to breathe in grout when it is in its powdered state. Always use a dust mask or respirator until the grout is thoroughly mixed with water and is no longer airborne. Remember all the grout needs is water to start hardening and your lungs are full of moisture.
There are many brands commercially available. If available in your area ALWAYS choose a brand that is Polymer fortified. The polymers add to the strength and flexibility of the grout. If this type is not available in your area you can use liquid admix in place of the water, these products will be sold side by side.
Check the manufactures recommendations on the back of the package. Grout comes in sanded (polymer fortified), unsanded, epoxy-based, and premixed versions. Our general recommendation for most projects indoors and out sanded polymer fortified grout.
Here are some great videos with grout demonstrations and helpful tips!
How to Grout a Mosaic Video
Grouting Broken Dish Mosaics
