In a large class of words, as a consequence of a series of historical sound changes, including the Great Vowel Shift, the presence of a suffix on the end of a word influenced the development of the preceding vowel, and in a smaller number of cases it affected the pronunciation of a preceding consonant.
When the inflection disappeared in speech, but remained as a historical remnant in the spelling, this silent ⟨e⟩ was reinterpreted synchronically as a marker of the surviving sounds.
This can be seen in the vowels in word-pairs such as rid /rɪd/ and ride /raɪd/, in which the presence of the final, unpronounced ⟨e⟩ appears to alter the sound of the preceding ⟨i⟩.
Although Modern English orthography is not entirely consistent here, the correlation is common enough to allow a rule-of-thumb to be used to explain the spelling, especially in phonics education, where a silent ⟨e⟩ which has this effect is sometimes called a magic, sneaky, or bossy ⟨e⟩.
The presence of a double consonant may indicate that the ⟨e⟩ is not silent and does not affect the preceding vowel (as in Jesse and posse).
This terminology reflects the historical pronunciation and development of those vowels, but as a phonetic description of their current values it may no longer be accurate.
However, the pronunciation of ⟨u⟩ before silent ⟨e⟩, found mainly in borrowings from French and Latin, is a consequence not of the Great Vowel Shift but of a different series of changes.
Non-silent ⟨e⟩ can also be indicated by a diacritical mark, such as a grave accent (learnèd) or a diaeresis (learnëd, Brontë).
This is especially common in some words that historically had ⟨f⟩ instead of ⟨v⟩, such as give and love; in Old English, /f/ became /v/ when it appeared between two vowels (OE giefan, lufu), while a geminated ⟨ff⟩ lost its doubling to yield /f/ in that position.
This also applies to a large class of words with the adjective suffix -ive, such as captive (where, again, the ⟨i⟩ is not lengthened, unlike in hive), that originally had -if in French.
Also, the feminine forms of some words of French origin end in a silent ⟨e⟩, for example fiancée, petite and née.
Historically, following the French usage, it was the practice to add a silent ⟨e⟩ at the end of words for aesthetic purposes.
A silent ⟨e⟩ is usually dropped when a suffix beginning with a vowel is added to a word, for example: cope to coping, trade to tradable, tense to tension, captive to captivate, plague to plaguing, secure to security, create to creator, etc.
In Chaucer's Balade, the first line does not scan properly unless what appears to current eyes to be a silent ⟨e⟩ is pronounced: Gilte ends in the same sound as modern English Malta.
One of these is known as "compensatory lengthening"; this occurred when consonants formerly present were lost: maid is the modern descendant of Old English mægde.
It qualifyeth no ending vowell, bycause it followeth none in the end, sauing i. as in daie, maie, saie, trewlie, safetie, where it maketh i, either not to be heard, or verie gentlie to be heard, which otherwise would sound loud and sharp, and must be expressed by y. as, deny, aby, ally.
It altereth also the force of, c, g, s, tho it sound not after them, as in hence, for that, which might sound henk, if anie word ended in c. in swinge differing from swing, in vse differing from vs. Mulcaster also formulated the rule that a double letter, when final, indicated a short vowel in English, while the absence of doubling and the presence of silent ⟨e⟩ made the vowel long.