Environmental sampling is the science of collecting and analyzing data to address questions in diverse fields, such as ecology, environmental engineering, environmental policy, fisheries, forestry, and wildlife science. The goal of sampling is to describe collective properties of populations defined as a universe. These collective properties are estimated using information from a subset of the universe called the sample. The universe may consist of discrete objects such as lakes, wetlands, stream segments, forest stands, plant or animal populations, environmental organizations, or recreational users, or it may be defined spatially, for example by delineating an area on a map. Environmental sampling objectives typically address questions of status and/or trend. Status refers to current values of population attributes. How many acidic lakes are there in the northeast US potentially sensitive to acidification and what are their characteristics? How many individuals of a rare plant population exist, and what is the geographical distribution of this population? What is the status of a nation’s wetlands? Trend focuses on how populations are changing over time. Are certain amphibian populations declining in South American forests? Is tree disease increasing following a damaging ice storm? How much agricultural land is being converted to residential and commercial use?