Gaskets are found in the space between many components in a vehicle which need that gap sealed. Many materials, especially dissimilar metals, don't seal well on their own, and gaskets are used to fix this problem. They are often made out of moderately soft materials which can withstand a large amount of heat and pressure.
Sometimes when a component needs a gasket but a form-cut gasket isn't available, or there is a custom part which no one would make a gasket for, gasket makers are used. There are a wide variety of gasket makers available, including oil resistant, high temperature, coolant resistant, copper-infused, rigid/high torque, and some that don't solidify.
Choosing the right gasket maker for the particular part connection. In some situations, a formed gasket can work better than a pre-molded gasket, while in other situations, such as when replacing head gaskets, no gasket maker can handle the stresses.
- Three Bond
Gasket Maker Manufacturers/Brands
Further reading: More About Gasket Makers
Gasket sealers are glue-like chemicals that help gaskets bond to the surface of parts. Three common types of sealants are hardening, which dries to form a solid seal, non-hardening, which doesn't dry but sticks in place, and tacky, a middle ground which assists with some gasket installations where it helps to have a gasket held in place while a part is installed.
Some gaskets are meant to be used without sealant, and some sealants make reusable gaskets one-time-use gaskets. Always check the gasket instructions for warnings.