Since the first humans evolved, they started making clothes and outfits that either protected them from extreme cold or warm weather. They used animal skin or fur to protect themselves from the cold and this was part of the brief history of insulation.
The Greeks and Romans discovered a special material called asbestos and they used it for many purposes and it helped them a lot in insulating their homes and their villages/towns. This later evolved into an extremely useful material for insulation and many still use it for the same purpose.
The most common types of materials used for loose-fill insulation include cellulose, fiberglass, and mineral (rock or slag) wool. Cellulose is primarily made from recycled newsprint. Most fiberglass contains 20% to 30% recycled glass. Many of the methods used for insulation are cheap and/or environmentally friendly.
In many cabins and cottages that were built decades ago, used the same insulation method as the Greeks and the Romans; asbestos, but it still functions well. Many people also have an attic which is either cold, warm, or maybe moderate (With the right amount of insulation). This depends on which methods and materialS you use to insulate it. For example, Mr. V.B has a cold attic and he probably "insulates" it by letting cold air enter from one side and exit from another side or from one window to another window. This may affect what you store in there as well, since if you store batteries in there, their power will drain. If you have ice cream in there it will take more time to melt than in a warm or moderately insulated attic.
The cost for insulation may vary as the materials used change. For example, if you insulated your house with sprayed polyurethane foam SPF it will cost more than cellulose per square feet. However, it is said that cellulose will slowly "get used" and will no longer have an affect on the insulation in your house. Also, sprayed polyurethane foam SPF will be more durable and might last longer ( It depends). However, the sprayed polyurethane foam SPF will cost more than the cellulose.
These conditions depend on when and where you want insulation. For example, in the summer, if you want to insulate a cabin and it is 30 C outside (Average), and you wanted to insulate that cabin for 15 years and said you wouldn't pay more than a 20 USD for a 100 square foot cabin, you would be recommended to get cellulose, but it would last very long and will meet your requirements. However for more than 30 years of insulation, you would need to spend mor for the other types of insulation.
Fact- The R-Value is really important for seeing if something is a good insulator.
There are two types of insulation that are used widely. Convectional "static" insulation and dynamic insulation. In dynamic insulation, the cold air from the inside of a house (for example), goes out of a pipe and the heat from the outside heats the cold air going outside of the pipe. At the same time, another pipe in the same house takes in hot air and the temperature inside turns the warm air into cold air. It then goes out of the other pipe and it goes on in a loop.
For convectional insulation, the hot air from the outside goes in towards the middle of the room to make it colder. The hot air comes in through another open place and the warm air turns colder and more warm air goes in and it maintains a steady temperature.
"Insulation is a barrier that minimizes the transfer of heat energy from one material to another by reducing the conduction, convection and/or radiation effects."- (Copy+Pasted but was really self-explanatory.) This sentence means that insulation minimizes the heat energy from getting to a particular place and it is insulated by preventing conduction to take place.