Using the vector tiles output — OpenGeo Suite 4.8 User Manual
GeoServer supports “vector tile” output in addition to the more standard image tile output. While the standard WMS output will generate a georeferenced map image, a vector tile contains georeferenced vector data, clipped into tiles for easy retrieval. On the other hand, the main disadvantage of vector tiles is that the geographic data may need to be pre-processed to allow the client to do the drawings it requires (similar to preprocessing data for image maps). With this in mind, vector tiles should only be used for rendering. GeoServer can also produce vector tiles in three formats: GeoJSON, TopoJSON, and MapBox Vector (MVT). These are also supported by OpenLayers 3 and other clients. We’ll be publishing our vector tiles through GeoWebCache and publishing the layer in a custom OpenLayers application. For this tutorial, we’ll be using the built-in layer opengeo:countries to show off the capabilities, though with slight modifications, any layer will do. Since these tiles are rendered in the client, we need only change the styling instructions inside the client application. No changes to GeoServer are required, and tiles will not have to be regenerated. Source.