The twenty-first century presents humanity with unprece-
dented energy challenges that require innovative solutions to en-
sure sustainable development while addressing climate change
concerns. Among these solutions, hydrogen has emerged as
a promising energy vector with the potential to revolutionize
our energy systems. This chapter establishes the fundamental
understanding of hydrogen as an energy carrier, tracing its his-
torical significance, examining its distinctive chemical proper-
ties, comparing it with conventional fuel sources, analyzing its
position in the global energy landscape, and addressing safety
considerations that often cloud public perception. As we stand at
the cusp of a potential hydrogen economy, understanding these
foundations becomes crucial for researchers, policymakers, and
industry practitioners alike. This chapter provides the scientific
and technical groundwork necessary to comprehend the multi-
faceted role hydrogen may play in our energy future, setting the
stage for subsequent discussions on production methods, storage
technologies, and applications across various sectors.