Chords, voicings and ciphers are some of the definitions that usually confuse us when we start in modern harmony. For this reason, we will make a brief review of each of these elements, which will help us when studying.
A chord is a group of notes that sound simultaneously and is usually structured by intervals of thirds. There are basic chords called triads composed of three notes (fundamental or 1st, 3rd and 5th); seventh, tetrad or cuatriada chords, which have one note more than the triads (fundamental, 3rd, 5th and 7th); and chords with more than 4 notes that are usually seventh chords with the addition of extensions or tensions (9th, 11th, 13th). The triads are often used in children's music, folk music, manners and less complex popular music. On the other hand the seventh chords and the chords with greater extensions are found in more complex popular music such as melodic pop, jazz, blues, bossa nova, funk, etc.
In theory, all chords are formed through overlapping intervals of thirds, however in practice these chords are rarely played in those closed arrangements.
Finally, let's look at the encryption topic. Encryption can be understood as the name of the chord, which gives us the necessary data to build a chord. In contemporary harmony the American cipher is used, where each musical note is identified with a capital letter from the note.
In addition to that letter, the type of chord is usually specified (m7, maj7, 7, m7b5, etc.) and sometimes also the extensions (9, 11, 13, etc.).