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.
Eau de toilette and cologne are the most popular forms in which fragrance is sold, and are particularly appropriate for the summer. Eau de parfum. After the top notes have died away, the middle notes or heart notes of a perfume become noticeable.