Litter Decomposition describes one of the most important processes in the biosphere – the decay of organic matter. It focuses on the decomposition process of foliar litter in the terrestrial systems of boreal and temperate forests due to the greater amount of data from those biomes. The availability of several long-term studies from these forest types allows a more in-depth approach to the later stages of decomposition and humus formation. Differences between the decay of woody matter and foliar litter is discussed in detail and a different pattern for decomposition is introduced. While teachers and students in more general subjects will find the most basic information on decomposition processes in this book, scientists and graduate students working on decomposition processes will be entirely satisfied with the more detailed information and the overview of the latest publications on the topic as well as the methodological chapter where practical information on methods useful in decomposition studies can be found. Abundant data sets will serve as an excellent aid in teaching process and will be also of interest to researchers specializing in this field as no thorough database exists at the moment.