Gravitational Lensing is a natural phenomenon that magnifies light around galaxies. The phenomenon occurs when a huge amount of matter, such as a massive galaxy or cluster of galaxies, creates a gravitational field that distorts and magnifies the light from objects behind it, but in the same line of sight.
This makes dim, faraway objects that otherwise would be undetectable, like an individual star, visible. The effect allows researchers to study the details of early galaxies too far away to be seen otherwise with even the most powerful space telescopes.