Tachyons are hypothetical particles that are theorized to travel faster than the speed of light. According to the principles of Einstein's theory of relativity, as an object approaches the speed of light, its mass increases, requiring more energy to accelerate further. Tachyons, however, would have an imaginary mass, allowing them to exceed this speed limit without the same energy constraints. These particles have not been observed in experiments, and their existence remains purely theoretical. If tachyons were real, they could have implications for quantum mechanics and causality, potentially allowing for phenomena like time travel or instantaneous communication across vast distances.