Pipes are the connectors for filters. The role of a pipe is to pass messages, or information, between filters and components. What we must keep in mind is that the flow is unidirectional, and the data should be stored until the filter can process it. This is shown in the following image, where the connector can be seen between the filters:
The Pipe-and-Filter architectural style is used to divide a larger process, task, or data into a sequence of small and independent steps (or filters) that are connected by pipes.