Paul Lazarsfeld was an influential sociologist and communication theorist, born in 1901 in Vienna, Austria. He is best known for his work in the field of mass communication and public opinion research. Lazarsfeld developed innovative research methods, including the panel study, which allowed for the analysis of changes in public attitudes over time. Lazarsfeld co-founded the Columbia University Bureau of Applied Social Research, where he conducted significant studies on the effects of media on society. His research contributed to the understanding of the two-step flow of communication, highlighting how opinion leaders influence the attitudes of others. His work laid the foundation for modern sociology and communication studies.