Why do Gas Cylinders & Plastic Chairs have holes?

Why do Gas Cylinders & Plastic Chairs have holes?

                                                    If you place a bucket on a wet surface for a few minutes, you may notice that the wet area surrounding the buckets becomes dry, but the area surrounding the bucket remains wet.

Let's Come to do the topic, Why do Gas Cylinders have holes underneath it?

                                                    Consider the case where the gas cylinder does not have holes, which means that wet water would be contained within it, as stated in the paragraph 1. In case of wetness, the cylinder will suffer from reduced air circulation. Moreover, the water between the body and the ring will shorten the life of the cylinders due to corrosion and damage, as well as gas leaks. This is why holes are necessary to drain the water.                        

                                              Well, then why do plastic stools and chairs come with holes? Isn't that for easy portability?

                                            Similar to the above ideology, Plastic Chains also have holes for air ventilation of our back portions, and if they are arranged one above the other,

  the holes allow free motion without a piercing effect from pressure established for a long time.