ask is one of the foundational primitives in NetLogo. It allows us to ask one or more agents (i.e., turtles, links, patches) to follow a provided set of rules. When ask is used with more than one agents, each agent will take its turn in a random order.

For example, the following code would make all the turtles in a model to move forward one unit and all the patches in a model pink.

ask turtles [ fd 1 ] 
ask patches [ set pcolor pink ]

We can also provide more than one command with an ask primitive. For example, the following code would make all the turtles put their pen-down, and then turn right by ten degrees and go forward one unit 36 times, which would draw a circle.

ask turtles [
    pen-down
    repeat 36 [
       right 10
       forward 1
    ]
]

Things to keep in mind when using ask:

• You can use the ask primitive with the custom turtle types that you define with the breed primitive.
• You can ask individual turtles to follow a set of rules using the form turtle n, such as ask turtle 1 [...], ask turtle 2 [...]
• You can ask individual patches to follow a set of rules using the form patch x y, such as patch 3 0 [...].
• You can use the with primitive to ask an even smaller subset of given agents such as ask turtles with [color = red][ ... ] or ask patches with [pxcor = 5][ ... ].
• You can use ask with turtles, links, and patches.
• If you write a code outside an ask statement, NetLogo will try to ask the observer to run the code but you cannot write a code such as ask observer [...].
• Note that each NetLogo primitive has a scope. If you use a primitive within an incompatible ask statement, NetLogo will show an error. A primitive can be observer-only (e.g.,create-turtles, diffuse), turtle-only (e.g., forward, hatch), patch-only (e.g., sprout, max-pxcolor) or link-only (e.g., tie, thickness). On the other hand, some primitives can be used within multiple scopes (e.g., pcolor, neighbors) and the utility primitives are scope-independent (e.g., mean, with).

In the model below, we want the fish to swim around randomly and the stars to just rotate, and we want all the turtles (fish + stars) to grow little by little. To make them follow these actions, we just use the ask primitive !