From the post:
Powered armor—high-tech defensive suits that move under their own power rather than using the muscles of the wearer—have a long history in science-fantasy stories, dating all the way back to E.E. "Doc" Smith's 1937 Lensman novel Galactic Patrol (one reason the Lensman books appear in the Starfinder Core Rulebook's Inspirational Media list). The conceptually serve as armor, steed, and sometimes even weapon for super-advanced knight of high-tech settings, allowing a character to act as science-fantasy cavalry. There are five suits of powered armor in the Core Rulebook, which is just enough to give an idea of how such gear works in the game, but certainly isn't anywhere near enough to cover all your possible powered armor needs.
Happily, there's a good deal more in Starfinder Armory.