City directories serve as key resources for identifying individuals in a specific location and timeframe. They can provide a general idea of where your forebears resided and pinpoint their exact locations during census years, while also establishing connections with other sources apart from censuses.
Typically, city directories are organized into several sections. For genealogists, the section of greatest interest is the alphabetical list of names, as it might contain information about your ancestors.
Source
Child, Hamilton; Gazetteer and business directory of Chittenden County, Vermont, for 1882-83; Syracuse, NY, USA: Hamilton Child, 1883.