High Quality Content by WIKIPEDIA articles! While the six strings have been standard practice since the 19th century, guitars featuring seven, eight, nine, ten or even more strings have been used by guitarists that wants to increase the range of pitch available from the guitar. Some types of these guitars can be specific for different cultures such as Russian and Brazilian guitars. During the 90`s the seven string guitar became popular among metal bands such who used the additional string for extra low end.