What is the difference between intermediate operators and terminal operators in data streams or sequences?

Intermediate operators (intermediate) in data streams (Streams in Java) are operations that return a new stream and allow chaining calls. They are lazy, meaning they do not execute immediately but only when a terminal operator is invoked. Examples: filter(), map(), sorted().

Terminal operators (terminal) are operations that complete the stream processing, return a result or side effect, and trigger the execution of the entire chain. After a terminal operator, the stream cannot be used. Examples: collect(), forEach(), reduce(), count().

Example:

List<String> list = List.of("a", "bb", "ccc");
long count = list.stream()
    .filter(s -> s.length() > 1) // intermediate operator
    .count(); // terminal operator

Here, filter is not executed immediately but only when count is called.