In this publication a state of the art of the Brain-Computer Interfaces ( BCI) is made (August 2019) They work because they are able to detect the signals sent to the neurons of our brains between the dendrites and the axons that connect them. These small parts are the differences in the electrical potential expressed by the ions in each neuron. Scientists can find and measure these signals using implantable electrodes. The signals are converted into digital information that is then translated through algorithms that have been developed over many years of thorough research and experimentation. So the signals from our brain become an artificial intelligence director that can then be used to control specially enabled prosthetic limbs and wheelchairs and move cursors and click on monitors. The software can also be trained to recognize signals that represent very specific ‘thoughts’ that represent numbers and letters, allowing writing for people who otherwise could not physically write. The holy grail for the medical community is to use BCIs in neuroprosthetics to improve the lives of people with disabilities.