Many folk songs have been around so long that nobody is entirely sure who their composers were. Often these songs are passed down within a community, and they evolve over time to address the issues of the day. Such songs include "We Shall Overcome," and "I Shall Not be Moved," as well as other spirituals.
Other timeless folk songs have definite origins, such as Woody Guthrie's "This Land is Your Land," or Pete Seeger's "If I Had A Hammer." These songs are often so poignant, honest, and timeless, that they become enmeshed into the culture, and are known by just about everyone.
Folk songs are typically about a community of people, and the issues they feel are important to them.
Contemporary folk songs cover topics from love and relationships to racism, terrorism, war, voting, education, and religion, among other things.