The topic of GMO foods is in the news and debated online so often that the acronym for “genetically modified organisms” doesn’t need to be spelled out.

But while most people know what it stands for, many have only a general understanding of exactly what GMOs are and how they’re created.

The World Health Organization offers this definition for GMOs: “organisms (i.e. plants, animals or microorganisms) in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination.” Other terms beside genetic modification for the technology that creates GMOs are gene technology, modern biotechnology, or recombinant DNA technology or genetic engineering.

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“The foreign genes may come from bacteria, viruses, insects, animals or even humans. Because this involves the transfer of genes, GMOs are also known as ‘transgenic’ organisms,” according to the Institute for Responsible Technology (IRT).

The genetic modifications are meant to achieve positive results, such as making plants resistant to pests or making plants that contains higher levels of specific vitamins. But the practice is controversial. Many groups contend that GMO foods increase allergic reactions and may cause long-term health damage.

Some organizations, like the IRT, fight the use of GMOs primarily because little is understood about their long-term effects.

“The technology of genetic engineering is currently very crude. It is not possible to insert a new gene with any accuracy, and the transfer of new genes can disrupt the finely controlled network of DNA in an organism,” IRT’s website said. “Current understanding of the way in which DNA works is extremely limited, and any change to the DNA of an organism at any point can have side effects that are impossible to predict or control. The new gene could, for example, alter chemical reactions within the cell or disturb cell functions. This could lead to instability, the creation of new toxins or allergens, and changes in nutritional value.”

The process of tweaking the DNA of plants utilizes high-tech systems for inserting the genes and studying the effects on the plants. It was detailed by Popular Science magazine, which explored the science Monsanto uses to genetically modify seeds:

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• Identify the new trait you’d like to introduce to the plant.
• Determine what other plants or organisms already have that trait.
• Using gene mapping technology, Monsanto takes a minute sample from a seed and determines its genetic structure.
• Once the desired gene is identified in the original plant, it is “grabbed” and inserted into the new plant.

“There are a couple ways to do this, including using ‘gene guns’ that literally shoot pieces of DNA,” Popular Science wrote. “A .22-caliber charge fires a metal particle coated with DNA into plant tissue. Monsanto no longer uses the technique, but it's still widely used among other biotech companies.”

Instead, Monsanto uses a “Trojan horse” way of introducing new genes into plants, giving as an example a soybean that was created to produce omega-3 fatty acids. Scientists “used a slightly more delicate process, heating soybean seedlings to place them under stress and make them susceptible to a bug called Agrobacterium tumefaciens,” Popular Science said. “The organism specializes in invading plant DNA and tricking it into producing sugars and amino acids that feed the bacteria. Scientists can exploit this Trojan horse ability and insert new proteins into the plant's chromosomes.”

"This is now in all the plant progenitor cells," Ginny Ursin, a genetics researcher at Monsanto, told Popular Science. "The pollen will have that DNA in its genome, so when you have a pollination event and create new seed, that trait is advanced into the next generation."

It still takes additional time – two years for Ursin’s soybeans that produce omega-3s – to grow out the seedlings and make sure the genetic modifications occurred properly.

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