The pp fitting is plastic materials commonly used in plumbing. The pipe is strong and does not wear or leave an aftertaste like other traditional metal pipes. PVC pipes are connected at joints or fittings. These fittings may have many joints on one fitting.
There are two ways to connect pp fittings, one is to connect with glue, the other is to connect with thread.
The pp fitting is glued into the joint to create a permanent hold. This “glue” is not a traditional glue as it actually creates a chemical bond with the inserted pip