Such improvements can mostly be classified to primarily fall within either of two categories: primarily relating to "core technology", i.e. "absorbency" in the broad sense of the word, or primarily relating to "chassis technology", i.e. fit.
The first addresses how to pick up and retain the body waste (generally in some state of fluidity) in an "absorbent (or core) structure", whereby the waste material is acquired by the article (picked up), then conducted away from the location of acquisition (distribution), and then stored (retained).
The second category deals - generally - with the so called "chassis elements" to contain the body waste within the confinement of the article. This can be done by separating the absorbent (core) structure and the outside, e.g. wearers garments or skin, by using an impermeable backsheet. Moreover the chassis should prevent bodily exudates from escaping through the space between the absorbent article and the body of the wearer, which can be achieved by elasticized gatherings at leg and waist openings. Other chassis aspects are enabling application of the article to the wearer - e.g. by providing closure means such as tapes – that are strongly correlated to the “fit”.
Often the terminology "comfort" for the wearer was predominantly addressed by improving chassis elements, such as by adopting the chassis elements of the diaper to provide good "fit" of the article and to be soft and cushioning. It is also well established that reducing the thickness of the article by reducing the primary thickness cause, i.e. the absorbent (core) structure, helps to improve comfort. This however was always a question of balance between liquid handling performance and thickness. Also a substantial amount of cushioning was considered necessary for comfortable diapers.
The development of absorbent (core) structures of particular thinness has also other beneficial aspects making such a development the subject of substantial commercial interest. For example, thinner diapers are not just less bulky to wear and fit better under clothing they are also more compact in the package, making the diapers easier for the consumer to carry and store. Compactness in packaging also results in reduced distribution costs for the manufacturer and distributor, including less shelf space required in the store per diaper unit.