Composed of a single proton and a single electron, hydrogen is the simplest and most abundant element in the universe. It is estimated that 90% of the visible universe is composed of hydrogen. Hydrogen is the raw fuel that most stars 'burn' to produce energy. The same process, known as fusion, is being studied as a possible power source for use on earth. The sun's supply of hydrogen is expected to last another 5 billion years. Hydrogen is a commercially important element.
Eau de toilette is a lightly scented cologne used as a skin freshener. The term toilette/toilet used in this context describes the process of washing and personal grooming. Eau de toilette is also referred to as aromatic waters and has a high alcohol content.
Typically Eau de Parfum is more expensive than Eau de Toilette due to the higher concentrations of essences contained therein. Both Eau de Parfum and Eau de Toilette are sold in medium volume as one needs to use more than perfume. And lastly, Eau de Cologne, has up to a 7% perfume concentration.