A stem cell, by definition, is an undifferentiated cell of a multicellular organism that is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation. Which essentially means that they are these remarkable little cells that have the potential to develop into multiple different cells in the body during early life and growth. They also, in many tissues, serve as an internal repair system, dividing without limit to replenish the diminishing cells.
There are two main stem cells. The Embryonic Stem cells and the Adult stem cells. The Embryonic stem cells are isolated from the inner cell mass of the blastocysts of preimplantation-stage embryos. These stem cells require specific signals from the cell requiring them. If they are injected directly they will split into different cells that may not need them and therefore cause tumors developed by what is called an abnormal pluripotent cell development.  
Embryonic stem cells are a potential source for regenerative medicines tissue replacement after injury or disease. The other main stem cell are known as Adult stem cells, the use of these stem cells is much less controversial than the use of embryonic stem cells because these do not require the destruction of an embryo also the adult stem cell are obtained from the required or intended recipient there is no risk of immune injection. Adult stem cells have been used for years to successfully treat things such as leukemia and several types of blood/bone cancers.
When these stem cells do divide they have essentially the potential or the choice to stay as they are, a stem cell, or they can become another type of cell with a more specialized function in the body such as a muscle cell, a red blood cell etc. In addition to this, stem cells have many other pertinent functions in the human body, one being by watching stem cells mature into different types of cells found in such places as bones, muscles and other important organs. Scientist, researchers and doctors can better understand how certain diseases in such places develop how they can further cure them better. Another amazing function to these stem cells is the ability for doctors to test new drugs in them. This makes it so doctors can test the safety and quality of new drugs and will definitely have a direct impact in the development cardiac toxicity.
Every single person on this planet developed from a fertilized embryonic stem cells, and our critical organs are maintained daily by Adult stem cells. So what is next for Stem cells? Well the future of stem cell biology and their use in treatments and biotechnology lies in the ability of humans to essentially unravel what makes these stem cells tick. The goal of scientists working with stem cells is to ultimately control cell differentiation. This would allow stem cells to create any organ or tissue in the body from a single stem cell. Also the condition for which stem cells provide the most promising advances are those that involve cell death, this is because stem cells are essentially internal repair systems for damaged or diseased tissue and organs.  
An additional goal of scientists and researchers of stem cells is to further enhance the cell by different techniques; one example of
this would be genetically modifying them to ensure they express particular proteins. Stem cells have a variety a different uses but one of the most groundbreaking in today’s world is studying stem cells in search of a way to better a doctor’s or scientist’s medical perspective. In fact, because stem cells can give rise to any type of tissue in the body, they provide nearly limitless potential for medical applications.  
My stand on Stem cells is somewhat mixed. In a way that I agree with one almost absolutely, but am not so sure on the other. Now, I am all for the use of Adult stem cells. This is because they are much less controversial than embryonic stem cells and I believe this is because they are so much less dangerous and threatening than essentially destroying the Embryo in Embryonic Stem cells. On the other hand, Embryonic stem cells are much more versatile and flexible, they have the potential to develop into almost any type of cell in the human body, and although Embryonic stem cells have a much larger number of cells to differentiate from but, researchers are finding more now that Adult stem cells also have much more plasticity than originally thought, which means they have the ability to differentiate into a greater range of specialized cells. 
Next I would like to address another key controversial issue in the world of Stem Cells: Stem Cell research. Do I agree with this? Absolutely. I honestly don’t see why someone wouldn’t. Both Embryonic and Adult Stem cells have the amazing potential to cure internal injuries in the tissue and organs and by researching and studying these Stem cells, scientists and doctors can further and better their knowledge of these magnificent things to potentially cure what used to be known as incurable diseases, such as Alzheimer’s, Stroke, Multiple Sclerosis, etc. To a point I do understand that these can be dangerous, and of course very expensive. But to have a second chance at possibly saving some one’s life, I believe that these are very important. By furthering the research and biotechnology of these wonderful Stem cells, doctors and scientists can get the remarkable chance to say that they have saved someone’s life or cured someone by sticking with the research and bettering these life saving miracles.
In Conclusion, the facts and knowledge I have gained from researching Stem cells will be something that sticks with me for a long time. It is amazing how one tiny thing can make such a big difference. I also loved the fact that it doesn’t take a scientist to research and have an opinion on stem cells. Essentially anyone interested can study Stem cells.