# LDK Architecture
LDK's core components are shown in the center box labeled lightning
. Boxes
with dotted borders are LDK's batteries — these must be configured with either
off-the-shelf or custom implementations that you provide.
EventHandler in the diagram is not so much a necessary LDK battery, but instead
refers to the fact that LDK generates events that the user should handle (e.g.
the PaymentReceived
event).