This document discusses concepts in labor economics including human capital, labor unions, and collective bargaining. It defines human capital as the skills and knowledge workers obtain through education and experience. It describes labor unions as organizations that collectively promote members' interests by negotiating with employers. Common union types include trade unions, industrial unions, and public sector unions. Collective bargaining is the process through which unions negotiate wages and work conditions with employers via contracts that typically last 1-3 years. Options if agreements are not reached include conciliation, voluntary arbitration, compulsory arbitration, and strikes or lockouts.