Sol-fa
An English solmization system.
What it means
Sol-fa, more fully Tonic Sol-fa, is a method of singing by syllables developed in nineteenth-century England. It rests on movable do: the syllables designate degrees of the respective key, not absolute pitches. Characteristic is the abbreviated writing, in which every degree is represented by its initial letter — which is why the seventh syllable became ti, so that it would not share the same letter with sol.
Musical use
The system arose from the intention of making polyphonic singing possible for laypeople without knowledge of notation, and was widespread in English choirs and in school teaching. This included a notation of its own, in which melodies were represented solely by letter abbreviations, strokes for duration, and colons for bar organization — musical notation in the usual sense was not required.
From this tradition also come the hand signs later taken over and further developed within the music education promoted by Zoltán Kodály. In minor, one usually starts from la, so that the relation to the relative major is preserved.
For ear training the method is effective because it connects function and sound: whoever sings ti sings the leading tone and feels its pull. Used to supplement musical notation, it remains in use to this day.
It is named after John Curwen, who developed the method from 1841 onward, building on preliminary work by the Norwich schoolteacher Sarah Ann Glover; the syllables are doh, ray, me, fah, soh, lah, te, together with a letter notation of its own that manages without a staff. Carried by the Victorian movement for social reform and "rational amusement" among the working class, the method spread quickly through schools and lay choirs; through British missionary societies it reached, among other places, India, Madagascar, China, Japan, and South Africa.
Performance practice
Use the syllables to work out melodies before you play them — especially the semitone positions become ingrained this way. Practise polyphonically: having two groups sing on syllables is the fastest path to secure intonation. And do not switch between movable and fixed do.