Effects change the way that an audio or a video clip is shown in your video. They can be used for some little improvements, like filtering color blurs in the image or hum interference in the sound, or for surreal, impressive modifications like turning an image to its negative form, changing colors, adding a "vinyl-like" sound to your clips, and so on. They can be combined in a multitude of ways. Once the effects are provided by the editor software, its use depends only on the user creativity --- ok, some processing power too :)

In the following pages you can see in details which effects are available in Kdenlive, with descriptions of what they do and the meaning of their settings:

Using effects in your project edit