DIA son unas siglas que pueden referirse a:

• Agencia de Inteligencia de la Defensa
• Declaración de Impacto Ambiental
• Dirección de Investigación Antimafia
• Supermercados Dia

«Día» - «Dia», o «Días»- puede referirse a:

• Dia, programa de diagramación de código abierto;
• Dia, cadena de supermercados de descuento;
• Dia, satélite de Júpiter;
• DIA, siglas de la Defence Intelligence Agency de los Estados Unidos de América, fundada en 1961;
• Dia, prefijo griego que significa a través de.

Se denomina día (del latín dies) al lapso que tarda la Tierra desde que el Sol está en el punto más alto sobre el horizonte hasta que vuelve a estarlo. Se trata de una forma de medir el tiempo —la primera que tuvo el ser humano— aunque el desarrollo de la Astronomía ha mostrado que, dependiendo de la referencia que se use para medir un giro, se trata de tiempo solar o de tiempo sidéreo —el primero toma como referencia al Sol y el segundo toma como referencia a las estrellas—. En caso que no se acompañe el término "día" con otro vocablo, debe entenderse como día solar medio, base del tiempo civil, que se divide en 24 horas, de 60 minutos, de 60 segundos, y dura, por tanto, 86.400 segundos.

DIA or Dia may refer to:

• Defense Intelligence Agency, United States foreign military intelligence agency
• Department of Internal Affairs (New Zealand)
• Department of Indian Affairs, Canadian federal department
• Defence Intelligence Agency (India)
• Defence Intelligence Agency (Nigeria)
• DIA (South Korea), Korean army defence intelligence agency
• Direzione Investigativa Antimafia, an Italian law-enforcement agency

A day is a unit of time. In common usage, it is an interval equal to 24 hours. It also can mean the consecutive period of time during which the Sun is above the horizon, also known as daytime. The period of time during which the Earth completes one rotation with respect to the Sun is called a solar day.

A day is a unit of temporal measurement for a literal day or epoch of time. Day, DAY or Days may also refer to:

• Daytime (astronomy)
• Awareness day, a date set by a major organisation or government to commemorate a cause of importance on a national or international level

The Defense Intelligence Agency (DIA) is an external intelligence service of the United States specializing in defense and military intelligence. A component of the Department of Defense (DoD) and the United States Intelligence Community (IC), DIA informs national civilian and defense policymakers about the military intentions and capabilities of foreign governments and non-state actors. DIA also ensures intelligence assistance, integration and coordination across uniformed military service intelligence components, which remain structurally separate from DIA. The agency's role is wide-reaching, encompassing collection and analysis of defense-related foreign political, economic, industrial, geographic, and medical and health intelligence. As part of its national IC responsibilities, DIA regularly provides input for the President's Daily Brief.