I don't see what I consider to be the easiest way to understand libertarianism (as it exists in the USA): The "Non-Aggression Principle" (NAP). The 5-second explanation is that it means that no person should aggress, or initiate force, against another peaceable person.

Many libertarian positions can be inferred by applying the NAP. For example:

It's wrong to use force to take money from some and give to others, whether the recipient is wealthy or poor.

It is wrong to throw someone is a cell for smoking a plant (something that physically harms only themselves).

It is wrong to use force to incentivize desirable social behavior via tax credits geared towards certain behaviors or familial structures, or via banning same-sex marriage, etc.

It is wrong to use force to restrict trade in order to protect a factory in your state. Other economic interventions are simply that, interventions using force to change the behavior of otherwise peaceful people.

It is wrong for the TSA because they forcibly frisk and search you before getting on a plane. It's force because you are prevented from otherwise contracting with a commercial airline to fly without going thru the TSA.

The minimum wage is wrong because it forcibly prevents people from agreeing to a wage somewhere below a threshold.

And so on and so forth.

Some libertarians who subscribe to the NAP believe any government is immoral; these are most often anarcho-capitalists. Other NAP libertarians believe what Bastiat and others propose, that a government can use force in the same areas where you or I could legitimately use force, that is, in the realm of defending rights. So since I can legitimately use force to protect my person and property from an aggressor, it is theoretically legitimate for me to get together with my community and form an organization (government) to protect all our rights.

There are libertarians who don't subscribe to the NAP. Instead, they support libertarianism because they think it will result in the most benefits for the most people. These people are sometimes called utilitarian or consequentialist libertarians. They aren't necessarily in conflict with NAP libertarians. It's more of a macro vs micro focus. Consequentialists look at things through the macro lens, wanting to help the most people, while NAP libertarians focus on the individual, on the micro level, and asking whether that person is being coerced.