A large majority of countries have unitary governments.

Unitary systems far outnumber other kinds of government. As a result, it is most likely that you, dear reader, are a citizen of such a government. To have an influence over the policies your leaders produce, you need a good understanding of the government structure. The kind folks at YouthLead offer this page as a crash course in all things unitary.
What, exactly, is a unitary government?
A unitary government is any country where political authority rests with a single, central government, rather than several smaller governments.
To get a clear idea of this concept, let's compare the United States to Japan. The United States is federal, not unitary. Japan, however, is a unitary country. Political power in the US is shared by the local, state, and national governments. As a result, rules like road signs, agricultural regulations, and drug laws are written by different officials in different places, and enforced differently from place to place. Sometimes in the United States, laws written at the state level will vary from laws at the national level. As a result, two places in the US can have different rules about the exact same thing. In Detroit, Michigan, you can turn left at some red stoplights but in Washington, DC you cannot.
Unitary governments like Japan get around these inconsistencies by vesting only one government with the ability to legislate everything. In Japan, the government in Tokyo is the central authority on all policy areas. As a result, you could travel from the very south of Kagoshima to the very north of Oma, and never experience a change in driving rules, food regulations, or criminal statutes.

In the United States, each state is responsible for administering its own roads. As a result, the color and shape of road signs sometimes changes from state to state.
Local governments in unitary systems
Some countries, like San Marino or Andorra, are so small that it doesn't make much sense to seed power to local authorities. However, in our previous example, we talked about Japan, which is both unitary and huge! So how do bigger countries deal with having one government for enormous numbers of people and places?
Just because a unitary government centralizes authority in one place, doesn't mean cities and provinces have no local power. Every unitary country has its own way of handling local government. Some countries, like the Dominican Republic, have many small governments stationed around the country, with fewer and more specific responsibilities compared to the national one in the capital. Other unitary systems, like the UK or Spain, have a very strong central government that gives local groups special authority over things like local languages and elections. To return to our first example, below Japan's national government are the prefectures. The prefectures are the first point of contact for citizens with legal troubles or questions about policy. However, those governments are always subordinate to the national government.

Now we can see how, even though most countries have one government at the center of all politics, local decision makers can still have an important role in governing people.
Youth action and unitary systems
A common feature of unitary governments are agencies, national ministries, or departments dedicated to young people. These agencies take many different forms. Some unitary countries, like Australia, merge departments of job training, youth issues, and education into one national agency. In other countries, youth ministries pop in and out of existence as political leaders come and go.
In general, they deal with issues that are especially important for young people. These issues can range from things as simple as organizing sports leagues, to serious matters like LGBTQ+ rights.
Youth-centered agencies can be helpful and receptive contacts for young changemakers. Nonetheless, as with any kind of government, it is also important for young people to take action outside of government-provided spaces. In other words, sometimes you have to work from the outside-in. To that end, we hope this quick-and-dirty introduction will be helpful to any of the many young people looking to influence unitary governments, at the national or local level.

Heads of youth-related agencies are frequently far older than the youths for which they make policies. Stuart Robert is in his fifties!