As of our current understanding, Earth is the only known planet in the universe that can support human life without the need for extensive life-support systems. The unique combination of factors, including the right distance from the Sun, the presence of liquid water, a breathable atmosphere, and a suitable climate, makes Earth the ideal planet for humans to live on.
However, scientists have been searching for potentially habitable exoplanets (planets orbiting stars outside our solar system) that might have conditions favorable for life. These exoplanets are often referred to as "Earth-like" or in the "habitable zone," which is the region around a star where conditions might allow for the existence of liquid water on a planet's surface. Some of the exoplanets discovered so far have been categorized as potentially habitable, but their actual habitability and suitability for human life are still largely unknown.
It's important to note that even if we were to find a potentially habitable exoplanet, the challenges of traveling to and colonizing such a distant world are currently insurmountable with our current technology. The distances involved and the limitations of human physiology and sustainability in space make it extremely difficult to establish a self-sustaining colony on another planet outside our solar system. Therefore, for the foreseeable future, Earth remains the only viable planet for human habitation.