Glues have been found dating back to around 4000 BC. They came into being when a sticky material (collagen) could be extracted from bones, hides and skin. These types of starting materials along with other animal scraps were processed to produce a simple glue substance. With these same basic processes bone glue, hide or skin glue and fish glue are produced.
Plants have also been used to produce vegetable glue such as gum Arabic from the acacia.
So the term adhesive is a general term which includes products formulated from polymers produced in a modern chemical plant and are often called synthetic "resins", so named after the gooey substance found in pine trees, which was one of the first widely used adhesives.
The definition of an adhesive is "any substance applied to the surfaces of materials that binds them together and resists separation."
There are many manufactures and adhesives on the market today, and each product may be designed to work with specific materials to give the best possible bond.
I personally only use a small number of glues for all my modelling, and listed below:
I use PVA as a general glue as it has so many uses for bonding the following materials:
Card, Paper, scenic materials including ballast and track work to a cork bed, and even attaching clear plastic aircraft canopies to the bodies.
The great thing with PVA is its available from most hardware stores and can be used straight out of the bottle or thinned down with water, and nearly always dries clear.
The great thing with this glue is that it bonds quickly and it excellent for bonding different materials together such as brass etch to plastic. There are even accelerators to help the curing process if working with complicated shaped parts, however this type of adhesive can be brittle when cured.
Two Part Epoxy
This adhesive gives a strong bond for the bigger parts or those joints that may be under a little more stress than other areas. Again this glue will bond many different materials and can even act as a waterproof barrier.
This glue has only a minor drawback and that is you may have a short working life once mixed, so preparation of the parts beforehand is a must.
Plastic Welding Glue
When making plastic model kits this glue chemically bonds the two parts together, giving a strong bond. The only drawback here is knowing how much to use, as to much can cause the plastic to melt or warp.
With all adhesives I recommend that you read and follow all the manufactures recommendations for safe handling and use.
As always, if you have any questions about weathering & detailing models for your layout, please feel free to email them to me and I will be pleased to assist you.