Midstream companies have been a solid base to my investment style for some time, for many reasons, but first, let's look at what a Midstream company is. Taken from williams.com, a midstream company which I don't directly invest in, Midstream companies operate the pipeline and gathering or transmission facilities that move the gas from the well (upstream) to our homes and businesses (downstream). Midstream operations also treat the product, remove water or waste products, compress it and get it ready for various markets downstream.