Suits

From Wikitroid, the Metroid wiki

Throughout the course of each game, Samus aquires one or more upgrade to her Power Suit. Each upgrade offers some new protection against specific environmental hazards as well as a reduction in damage taken (the degree of reduction varies significantly from upgrade to upgrade).

The Varia Suit upgrade lets Samus survive extreme tempertures, as well as reduce the damage she takes from enemy attacks. This armor is her most iconic suit upgrade

The Gravity Suit lets Samus move faster under water.

The Light Suit and Dark Suit protect Samus from dark Aether's atmosphere, with the Light Suit providing complete protection while the Dark Suit lowers the damage to one hp per second.