American history homework help

Communism as a political and economic force has been a major factor in global affairs for around one hundred years. The United States, and most of the west, considers it to be fundamentally evil and flawed, whereas others have (and still do) think of it as a great step forward in human civilization.
What seems to have been proven, however, is that does not work. It does not create thriving, prosperous societies. Every Communist nation has been a brutal dictatorship, and people that live under Communism come to hate it very quickly. Socialism, of course, is the economic foundation of Communism, and the two ideologies are closely correlated.
Here is the question: why does Socialism/Communism still have an appeal when it has repeatedly failed? Why do some people, often in poor countries, feel drawn to this philosophy despite its history?
Also, for decades the United States led the drive against Communism, often engaging in pretty underhanded tactics to thwart it. Were these actions justified? Please look up some examples.
Is there a way to bring an element of Socialism into society in a way that would be positive? After all, many institutions are quasi-Socialist, such public schools and social safety nets.
Make sure in your essay you explain how Communism and Socialism work on a basic level. Prove that you actually understand these concepts.