A key is a code of signs agreed that is used to transmit a secret or private message. The etymological origin of the term is found in the Latin word clavis, which means key.
According to DigoPaul, a key is also the sign or the combination of signs that allows you to operate certain devices or enter a restricted space. This use of the concept is very common on the Internet, where the keys or passwords allow a user to access their personal email account or other service (“The password for my email account is my daughter’s birthday”).
These two meanings of the notion of key are linked to its etymological origin, since the key functions as a key to access a secret message or private information and content.
On the other hand, a key is something fundamental or decisive, which allows to explain or justify something: “The key to the victory has been the performance of the goalkeeper”, “Tomorrow will be a key day in the trial for the triple crime”, “The key There is no such thing as success even though everyone strives to look for it.
In architecture, the stone used to close an arch or vault is known as a key.
The concept in music
In the field of music, a clef is a sign that is written at the beginning of the staff to determine the name of the notes that will appear next. The most commonly used clef in music is the treble clef.
The function of a musical clef is to locate the person who plays a certain melody within a tonality, using those notes that are harmonically associated with each other and associating them with the spaces and lines of the staff.
There are many possibilities for clefs and positions on the staff, yet only seven of these are used. It is important to point out that for a melody plotted on a staff to have meaning and coherence, it must contain a clef at the beginning; Furthermore, it may change throughout the piece. When modulations are carried out, it is not necessary to change the key, if it will return to the original key, but if the change is complete and will be maintained for the rest of the work, it is necessary to change the key that is used.
The instrument that plays the score must conform to the range of notes imposed by that key. The fundamental objective of the key is to clarify as much as possible the writing, avoiding as much as possible the clarifications so that the reading of said score is simple and the performer can also understand the thread that the composer had to choose one or another note, within a tonality.
Looking for greater clarity is that certain keys have fallen into disuse. Such is the case of the SOL clef in the third, because its tessitura and the name of the notes is exactly equivalent to the DO clef in the first and therefore it does not make much sense that there are different clefs to express the same thing and it was chosen for one, which has gained character academic and universal.
It is worth mentioning, in case it has not been clear, that the fundamental objective of the harpsichord is to mark the tessitura in which said piece should be interpreted. The fourth key of C being the most used in piano scores and indicates that it will start from the central C.