Callbacks

A callback is simply a function called at a certain point in time, with an optional set of arguments. There is no return value.

See: “Trigger→call”:http://chyrp.net/docs/class/Trigger-php.html#Trigger.call and Triggers

Filters

A filter takes the target for filtering as the first argument, and any additional arguments from there; the goal of a filter is to modify the target and return your modification. Modules (and in some cases, Feathers) interact with eachother (blindly); the filters stack onto eachother and produce one result.

See: “Trigger→filter”:http://chyrp.net/docs/class/Trigger-php.html#Trigger.filter