MSM stands for Methyl-Sulfonyl-Methane (Dimethyl Sulfone). It is not a chemical, it is a natural sulfur that occurs widely in nature. Sulfer plays an essential role in human nutrition. I started taking MSM for osteoarthritis in my thumb joint and C2/C3 neck joints. The pain had been chronic for 12 years. My pain level rarely reaches 1 or 2 now. I started with half a teaspoon daily for 3 days, then increased to a level teaspoon and worked up to the amount that stop the pain, which for me is one desert spoon full. I take this every morning after my breakfast in a large glass of filtered water. MSM does taste slightly bitter but you get use to it. I know when I have accidently missed a dose as my joints start to ache again. MSM takes out the inflammation in your body. It does not cure arthritis but it takes the pain away the inflammation, which really helps pain relief.