D is the fourth letter of the modern English alphabet and the ISO basic Latin alphabet. Contents. [hide]. 1 History; 2 Use in writing systems; 3 Other uses. Agust D 'Agust D ' Agust D's 'Agust D ', the first mixtape album, featuring 'Agust D ', ' give it to me. D is a systems programming language with C-like syntax and static typing. It combines efficiency, control and modeling power with safety and programmer Areas of D usage · Downloads · Dlang forums · DUB package manager.