Main technical features and functionalities
System:
Free, open source
Cross-platform: runs on Mac, Windows, Linux, et al
International character set support
Programming:
Fully programmable
Approachable syntax
Language is Logo dialect extended to support agents
Mobile agents (turtles) move over a grid of stationary agents (patches)
Link agents connect turtles to make networks, graphs, and aggregates
Large vocabulary of built-in language primitives
Double precision floating point math
First-class function values (aka anonymous procedures, closures, lambda)
Runs are reproducible cross-platform
Environment:
Command center for on-the-fly interaction
Interface builder w/ buttons, sliders, switches, choosers, monitors, text boxes, notes, output area
Info tab for annotating your model with formatted text and images
HubNet: participatory simulations using networked devices
Agent monitors for inspecting and controlling agents
Export and import functions (export data, save and restore state of model, make a movie)
BehaviorSpace, an open source tool used to collect data from multiple parallel runs of a model
System Dynamics Modeler
NetLogo 3D for modeling 3D worlds
Headless mode allows doing batch runs from the command line
Display and visualization:
Line, bar, and scatter plots
Speed slider lets you fast forward your model or see it in slow motion
View your model in either 2D or 3D
Scalable and rotatable vector shapes
Turtle and patch labels
APIs:
controlling API allows embedding NetLogo in a script or application
- extensions API allows adding new commands and reporters to the NetLogo language; open-source example extensions are included

Examples on how to use them to analyse Complex Systems
This model is useful to demonstrate the phenomenon of spontaneous self-organization of Complex Systems. It mimics the flocking of birds and the schooling of fishes. The self-organization occurs because every agent follows three specific rules: "alignment", "separation", and "cohesion".
"Alignment" means that a bird tends to turn so that it is moving in the same direction that nearby birds are moving.
"Separation" means that a bird will turn to avoid another bird which gets too close.
"Cohesion" means that a bird will move towards other nearby birds (unless another bird is too close).
When two birds are too close, the "separation" rule overrides the other two, which are deactivated until the minimum separation is achieved.
The three rules affect only the bird's heading. Each bird always moves forward at the same constant speed.
This module demonstrates that certain Complex Systems can self-organize without any leader.