Proxima Centauri B
Properties:
Mass: 1.60 Earth masses
Temperature: 234 K
Semi-Major Axis: 0.049 AU
Orbital Period: 11.18 days
Proxima Centauri B(depicted by an artist's impression above) is an exoplanet orbiting within the habitable zone of Proxima Centauri, a red dwarf. Proxima Centauri, as noted by its name, is the closest star to us in the universe at around 4.2 light-years away, making Proxima B the closest exoplanet to us.
As noted above, Proxima b has a very close orbit to its star but its temperatures aren't as high as Earth's because Proxima Centauri, the star the exoplanet orbits, is a red dwarf, so it's much cooler than the Sun.
Above is an artist's impression of the arid, but not entirely water-less surface of Proxima b.
Proxima b hasn't been established as habitable but it's unlikely that the surface would be habitable because the stellar wind from Proxima Centauri on Proxima b is 2000 times stronger than solar wind on Earth. That being said, many astronomers believe liquid water could exist on the surface.
However, there are more complications than just the planet itself when it comes to habitability. Proxima b orbits very close to its star so it is likely tidally locked, meaning only one side of the planet faces the star. This would mean the star-facing side would be extremely hot while the dark side would be extremely cold because there's no day-night cycle to keep temperatures relatively stable. This would mean that even if somehow radiation didn't play a factor from the stellar wind, the only habitable portion of the surface is the division between the day-night lines.
Citations/Attributions
Proxima Centauri b. Provided by: Wikipedia. Located at: https://en.wikipedia.org/wiki/Proxima_Centauri_b. License: CC BY-SA: Attribution-ShareAlike
File:Artist’s impression of Proxima Centauri b shown hypothetically as an arid rocky super-earth. Provided by: Wikimedia commons. Located at: https://commons.wikimedia.org/wiki/File:Artist%E2%80%99s_impression_of_Proxima_Centauri_b_shown_hypothetically_as_an_arid_rocky_super-earth.jpg. License: CC BY 4.0
File:Artist's impression of the planet orbiting Proxima Centauri. Provided by: Wikimedia commons. Located at: https://commons.wikimedia.org/wiki/File:Artist%27s_impression_of_the_planet_orbiting_Proxima_Centauri.jpg. License: CC BY 4.0