Fluent API means to build an API in such a way so that it meets the following criteria:

1. The API user can understand the API very easily.
2. The API can perform a series of actions in order to finish a task.

For example, we can do it with the chaining of methods

Turtle t = new Turtle("Spot", 0, 0, true, true);
t.penDown().hide().moveTo(10, 10).show().turn(-90).move(100).turn(+180);

instead of

Turtle t = new Turtle("Spot", 0, 0, true, true);
t.penDown();
t.hide();
t.moveTo(10, 10);
t.show();
t.turn(-90);
t.move(100);
t.turn(+180);