Slide and Grip hitches
Here you find slide and grip hitches. These hitches are meant to slide up a rope, but not down by themselves without you wanting them to slide down because they grip when they are loaded. They are part of the hitches family because you technically tie a rope around an object, in this case another rope.
Friction hitches do have many purposes for example they are being used by arborists in their climbing systems. Based on the type of climbing system used you will often see the VT Hitch and the Blakes hitch. But you can also use friction hitches to setup an adjustable tension system on a line for example when hanging a hammock or when setting up tent guy lines. Slide and grip friction hitches are also used in sports climbing and mountaineering activities. For example the Prusik hitch and the Klemheist are often used as a backup when rappelling with figure eight device or other friction device.
How well a slide and grip hitch "bites" depends on a lot of factors. The most important ones are the size and material of your climbing rope and the size and material of your Prusik cord. In general a more flexible Prusik cord will have a more aggressive bite then one that has more stiffness to it. Also make sure the Prusik cord is at least 3-4 mm thinner then your climbing line.
Slide and grip hitches are often used in a situation where your life depends on them so make sure you familiarize yourself with them in a safe environment before even consider using them in you climbing system.