Board Position is how strong a player's installed cards are vs their opponents installed cards.
Corp Advantage Board Position[]
Corporations board position is typically improved by installing and rezzing ice, and installing assets that provide advantages for them.
The Corp also often benefits from weakening the Runner's position by trashing programs with ice like Rototurret, or Trashing a Resource when the runner is tagged.
Runner Advantage Board Position[]
For Runners their board position is improved by installing Icebreakers, other programs, hardware like R&D Interface, and resources like Professional Contacts that give them an ongoing advantage.
Runners also commonly benefit from weakening the Corporation position by running and trashing assets, and by trashing or derezzing ice with Parasite, Emergency Shutdown, or Crescentus.
Board Position vs Tempo[]
A balancing act for both sides is that cards that help improve their board position often also cause a temporary loss of Tempo from the spent clicks and credits installing them. Clicks and credits that otherwise could have improved the tempo for the current player by being spent on options that give immediate but temporary results - like making runs, advancing agendas, or playing Events or Operations.