Intelligent agencies are a part of the secret services of a country. Hence, they are governmental agencies. The primary purpose of such agencies is the collection of intelligence data and later processing it. By that, we understand turning data to information and information to intelligence. They focus on either politics or the military.
The work may sound simple but is very complex. Data is the raw form. A piece of data by itself is not so vain. But, putting more data together and answering the questions which the data brought up creates information. Lastly, intelligence is a complete picture of what is happening. The state then uses intelligence to make decisions.
Further, the goal of these agencies is to protect the country and the citizens. They work in secret. That is a significant aspect as a leak could jeopardize their work. And, as a result, threaten the safety and security of citizens. But, they should not be mistaken for secret police as they do not have the same purpose nor police rights (with some exceptions).
Types of Intelligence Agencies
Different agencies have different scopes. Counter-intelligence works on the domestic level. Their goal is to intercept foreign influences. Hence, to prevent espionage, terrorism, and so on. Further, a domestic agency also operates on the domestic level. It also combats inside threats such as organized crime and terrorism. On the other hand, a foreign agency functions abroad. So, their work eases decision-making on an international level. All the agencies should cooperate.
However, it is well-known for these agencies to mix up in unjust behavior. There were many assassinations or interferences with elections. It was most common during the Cold War.
Of the many agencies, maybe to most famous are the American FBI and CIA, Russian FBS (and prior to that Soviet KGB), British MI5 or MI6, or the Israeli Mossad. But, more or less, every country has multiple agencies. Agencies have various rights and report to different organs. That is because they have distinct founders. The department of justice can have its agencies as can the department of defense, and so on.