The best known biotechnology of all is brewing - you know, making beer and wine and stuff. People use tiny plant-like organisms called yeasts to change sugar water (usually flavoured with something) into alcohol. Plant and animal breeding is another where people choose particular traits - qualities - which an organism has. An example is corn - maize. For centuries, this plant was carefully selected by Mexican farmers to favour one which gave bigger cobs with more and fatter grains of corn on each. (Today, everyone takes this for granted, not knowing their breakfast cereal or corn crackers are the result of all this careful work done many years ago and made freely available to everyone. And also today, companies would patent such achievements to stop anyone else from using them unless they pay money.)

But now, science has created new types of biotechnology such as cloning (making identical copies of organisms or cells) and, of course, genetic engineering - the subject of my guide. GE is based on the artificial manipulation and transfer of genetic material from any type of organism to any other type.
For more on this, look at What Is Biotechnology?, Union of Concerned Scientists, USA.