FODMAP is short for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These are short-chain carbohydrates and sugar alcohols that are hard to digest. If you experienced bloating, gas, abdominal pain, or other digestion issues, the reason might be the ingestion of too many FODMAPs. People with IBS or other stomach problems are more sensitive to them. Some studies show that a low-FODMAP diet can help ease symptoms such as bloating and abdominal pain. 
The five forms of FODMAP carbohydrates are fructose, lactose, galactans (legumes), fructans (wheat, onions, garlic), and sugar alcohols (polyols). Eliminating these for a period could immediately provide relief for people who often experience bloating without knowing the cause.
The purpose of the diet is not to entirely remove FODMAPs from your life. That is necessary only in the beginning until you realize which ones are problematic. After a while, you can start reintroducing them one by one to figure out which ones are the culprits. For example, you might conclude that you need to eliminate dairy products or legumes, but you can eat fruits and wheat products in moderation. There are also cases in which the body doesn't tolerate foods in their raw form; cooking them might solve everything.
Foods that are high in FODMAPs include most fruits, sweeteners, dairy products, some vegetables (cruciferous vegetables, beetroot, onions, garlic, leeks, mushrooms, artichoke, shallots, peas, asparagus), legumes, wheat products, soft drinks, and beer.  These foods are not unhealthy. Most of them have plenty of health benefits. When following a low-FODMAP diet, your goal is to get those benefits from sources that don't upset your stomach or colon.
Here is a list of foods low in FODMAPs:
Meat, eggs, and fish. You can eat these without worrying but pay attention to products that contain other ingredients that are high in FODMAPs.
Fats and oils. When it comes to these, you have a green light. Nonetheless, try to choose healthy versions.
Nuts and seeds. Pistachios are high in FODMAPs, but macadamia, cashews, almonds, peanuts, pine nuts, etc. are ok if they don't have added ingredients which are high in FODMAPs. These include nut snacks.
Fruits and vegetables. The list of fruits and vegetables low in FODMAPs is long, but there are also fruits and vegetables high in FODMAPs. For more info check a more detailed list.
Grains. Wheat, barley, and rye products might not be IBS friendly, but you still have other options such as oats, rice, quinoa, and tapioca.
Beverages. You can drink coffee and tea, but without cream or other high FODMAP ingredients. 
If you frequently experience digestive upset, the foods high in FODMAPs might be the reason. Note that the low-FODMAP diet serves people with IBS symptoms, and it will not help with weight loss. FODMAPs have plenty of health benefits; therefore, if they do not bother you, there is no need to eliminate them from your diet. 
To save you on shopping time, here are some recommendations:
Ketotarian Diet - An Introduction
What can vegetarians do to follow the keto diet? The KETOTARIAN diet is the plant-based version of the keto diet. But how can vegetarians follow the keto rules?
6 Proven Health Benefits of Ginger
Is ginger good for you? This food has anticancer, anti-inflammatory, and antioxidant properties. Here are 6 proven health benefits of ginger.
Does Milk Contain Sugar?
Cow's milk and breast milk have naturally occurring sugar (lactose), while nondairy kinds of milk might contain added sugar. Which types of milk to choose?
3 Foods Children Should Avoid
There is a long list of foods children should avoid, yet many sneak into your daily diet to make life easier. Here are the top 3 foods children should avoid.