Gamma

In Ancient Greek, the letter gamma represented a voiced velar stop IPA: [ɡ].

In Modern Greek, this letter normally represents a voiced velar fricative IPA: [ɣ], except before either of the two front vowels (/e/, /i/), where it represents a voiced palatal fricative IPA: [ʝ]; while /g/ in foreign words is instead commonly transcribed as γκ).

[5] The Ancient Greek /g/ phoneme was the voiced velar stop, continuing the reconstructed proto-Indo-European *g, *ǵ.

A double gamma γγ (e.g., άγγελος, "angel") represents the sequence /ŋɡ/ (phonetically varying [ŋɡ~ɡ]) or /ŋɣ/.

It is not to be confused with the character ɤ, which looks like a lowercase Latin gamma that lies above the baseline rather than crossing, and which represents the close-mid back unrounded vowel.