What is Homelessness?

Before delving into the issue of homelessness, it would first be a good idea to understand that multiple definitions of homelessness exist, each reflecting a greater magnitude of it. Some define "homelessness" to be when one has no home at all while others believe it to be even when one has a residence, just not a permanent one. However, researchers agree on this: homelessness is irregular, meaning that somebody that is homeless right now may not be in the future and vice versa. Irregular or not, as this problem grows to be an increasing concern worldwide, one cannot help but wonder why it occurs. Doesn't the United States have enough resources and wealth for all of its citizens? What is the United States doing politically to help reduce and hopefully stop homelessness? And in comparison, what has China been doing to address this problem? And lastly, is any one way bettter? My goal is to research the political approaches each country has brought to the table, as well as the social causes and perspectives each has.