Have you ever noticed the fungal growth on bread or the algae growth around ponds? Well, those greeny, sticky substance are known as microbes or micro organism (scientifically). In certain practical situation it becomes essential to control them. The study of microbiology has made it possible to  make  significant advances in agriculture, medicine, and food science areas.

Therefore, the term "Control of microbial growth", refers to inhibit or prevent growth of microorganisms. It can be done in two basic ways:
Killing microorganisms
Preventing the growth of microorganisms. It mainly involves the use of physical or chemical agents which either kill or prevent the growth of microorganisms. Basically, cidal agents are responsible for killing microorganism cells. The agents which inhibit the growth of cells, besides  killing them are known as static agents.

The complete destruction of viable organism is termed as sterilization in microbiology. Following are some of the methods of Sterilization:

Heat: It is one of the common ways to prevent the growth of microorganism. This method is basically dependent on the type of heat, time of application and temperature to ensure destruction of all microorganisms. One of the most thermoduric of all cells is considered to be the Endospores of bacteria, so their destruction guarantees sterility.
Incineration: This procedure mainly burns the organisms and physically destroys them. It is mainly applied for needles, inoculating wires, glassware, etc.
Boiling: It is believed that boiling at a temperature of 100o for 30 minutes, kills everything except some endospores.
Autoclaving (steam under pressure or pressure cooker): It is one of the most effective and efficient means of sterilization. The two main elements in this methods are time/temperature relationship. For rapid killing is ensured through higher temperature, whereas longer times are needed for larger loads, large volumes of liquid, and more dense materials. This method is perfect for sterilizing bio-hazardous waste, surgical dressings, glassware, many types of micro-biologic media, liquids, and many other things.

Besides these techniques there are many other forms which help in destruction of microorganism, such as Dry heat (hot air oven), Irradiation and more.