Burst is an active generator program which, when activated, generates +3 PWR and gives all agents +3 AP, but then -3 AP for the next 2 turns while the program is on cooldown. Burst can be chosen as a starting program, or bought from some Server Terminals for 300 credits.
The AP bonus and penalty apply to all agency-controlled units, including hacked drones, and the rescued Courier or Prisoner.
Burst is found in the Contingency Plan DLC.
The -3 AP penalty is quite severe, and applies for twice as many turns as the the +3 AP bonus. The penalty typically prevents agents from sprinting, and by extension sprint toggling, for the two turns after Burst is used.
In principle Burst can be used every 2 turns, to generate an average of +1.5 PWR per turn. In this case, the +3 AP bonus cancels out with the second turn of the -3 AP penalty, giving a net 0 AP and then -3 AP on alternating turns. Used this way, Burst generates a little more PWR than Power Drip, but the downside is worse than Labyrinth every other turn.
It is therefore usually best not to use Burst frequently, and instead reserve it for situations where the extra PWR or AP is needed urgently. Used this way, Burst can be an effective solution in an emergency, but you will want another PWR source in addition to Burst.
When playing with Burst and Seed, use another program on the same turn before Burst to avoid wasting Seed's benefit.