Probiotics are products that contain strains of bacteria or yeast similar to what we would find in different parts of our body. These bacteria would perform functions that are beneficial to the host and help maintain a healthy state of the space where they reside. They are also known as the "friendly bacteria".
Over the years, more and more studies have come out regarding probiotics and their benefits to the human body. Along with the many discoveries were also the many strains of probiotics that perform different functions.
We typically know about probiotics benefits in assisting our digestion and gut health. But they can also benefit us in multiple other functions as well (Also see: Proven Benefits of Probiotics).
Similar to our natural ecosystem, different types of bacteria exist in our guts, eyes, skin, respiratory system, reproductive system...etc.
Most of these friendly bacteria are cultured and produced. Lactobacillus acidophilus, for example, is one of the most well known and the biggest family we see in probiotics. They are found in our intestines. Acidophilus has one time been used interchangeably as probiotics for this reason. Some strains can also be engineered to perform certain functions.
Most probiotics should be labelled containing the organisms' genus, species, and stains. For example:
A common yeast probiotic called Saccharomyces boulardii would not have a specific strain, since it is not a bacteria.
We can also get probiotics from food such as yogurt, kimchi, miso, sauerkraut...etc. However, because the CFU (Colony Forming Units -number of live organisms) are less concentrated from food, also the probiotics strains are not as specific.
So, if you're needing therapeutic effects from probiotics, like preventing and treating antibiotics, like preventing and treating antibiotics associated diarrhea and irritable bowel disease, specific probiotics supplement will be much more effective.
Most of the probiotics have combination strains, but there is no "one size fit all" products. It is always wise to consult with a health care professional to assess your needs and find a product that has the best fit.