Brain-computer interfaces (BCIs) establish direct brain communication with external devices. Non-invasive BCIs like EEG are safe and accessible, but offer low spatial resolution. Recent AI advancements may improve their accuracy, potentially making them equal to invasive BCIs in certain situations. Invasive BCIs, like Neuralace by Blackrock Neurotech, offer higher resolution but require risky open-brain surgery. They are mainly used for therapeutic interventions and research, leaning towards restoring lost sensory or motor functions. BCIs have proven successful in treating disabilities like locked-in syndrome, restoring mobility to paralyzed patients, and even enabling brain-to-brain communication for new forms of interaction.