Subspace Communication

Starting Tech only allows you to give new orders to ships when they are in orbit around a star (or departed on the current turn - you can change your mind on the current turn).

This is the first level of technologies that allow you to send mid-flight order changes to ships when they are between star systems. The range is limited but increases with each step in this type of technology.

This acts as a "force multiplier" allowing you to cover more situations with fewer ships and react to evolving situations in strategic combat.

It is also possible to use this technology (with a little effort) to "station" fleets in interstellar space rather than at a star system.