The history of terms isn’t particularly relevant, though it is interesting. For example, “libertarianism” largely came from socialism, and “liberalism” largely meant “small government,” whereas today libertarianism is pretty close to what liberalism used to mean, and “liberals” are in favor of large government.

Here’s what I mean by each term:

• socialism - “Democratic ownership of the means of production,” as in, the government runs the economy
• Democratic socialism - large central government with a lot of subsidised services, like healthcare; the means of production are private owned, but heavily taxed
• libertarianism - “subscribes to the non-aggression principle, emphasizes radical individual freedoms and minimal taxation” - government services should be minimized to prevent top down abuse
• communism - the end goal of socialism, which is a stateless society where people share what they produce so everyone has enough (from each according to his ability, to each according to his need)

I think socialism as defined above is unworkable because bureaucrats will abuse their power, communism is unworkable because people are selfish, and Democratic socialism is tricky because a large state tends to restrict the freedoms of its people. That’s why I align with libertarianism, but am on the left end where I believe there should be wealth redistribution through something like UBI (I prefer Negative Income Tax), so you get most of the benefits of socialism (everyone gets what they need) without most of the bureaucracy (no application process other than tax return).