It arose directly from the Greek letter gamma and both capital and small Ge look like the capital letter gamma.
In standard Russian, it represents a voiced velar plosive except when it is devoiced to [k] word-finally or before a voiceless consonant and represents [gʲ] before a palatalizing vowel. Also, in some masculine genitive and accusative case word endings, it represents /v/ when found between two vowels. In south-western Russia, the sound becomes a fricative [ɣ], and sometimes [ɦ] in regions bordering Belarus and Ukraine. It is acceptable to pronounce certain Russian words with [ɣ] (referred to as Ukrainian "г"): Бог, богатый, благо, Господь, although, not all speakers use or agree with this. This sound is normally considered non-standard or dialectal in Russian and is avoided by educated Russian speakers. Бог (in nominative case) is always pronounced /box/.
In the adjective/pronoun ending -ого, -его letter г is pronounced as [v] (Russian only), including the word "сегодня" (from "сего дня") - "today" .
Letter г is devoiced to to [x], not to [k] in front of letter "к" in Russian in 2 words: "мягкий" and "лёгкий" and all the derivatives where "гк" are spelled together.
In Ukrainian, a voiced velar plosive is rarely present, and when present it is to be written with the Ukrainian letter ge with upturn (Ґ, ґ). In the Belarusian language, it was supposedly more frequent (to render words borrowed from Polish and Russian), but during the twentieth century the distinction in usage blurred significantly. Reintroduction of ge into the Belarusian alphabet is only proposed by some linguists and not supported officially.
Its HTML entities are: Г or Г for capital and г or г for small letter.