Strategies deal with when to make requests for data and determine how to prepare features before they add into a layer.
BBox is a simple strategy that requests new features whenever the map bounds are outside the bounds of the previously requested set of features. This strategy will only fetch data for the desired area.
A simple strategy that requests features once and never requests new data.
Before rendering new features to the Vector layer, the cluster strategy can group the features together in clusters based on proximity to other features. Please visit the Strategy section in Vector layer guide page to see how it works.
Similar to Cluster strategy in Vector Layer, the Marker Cluster strategy is used in Marker Layer to group markers together before adding to layer.