According to Wikipedia, a poster session is "the juried presentation of research information by representatives of several research teams at a congress or conference with an academic or professional focus."
During a poster session, many researchers and their posters are typically available in a conference room, accessible to circulating attendees. The poster session provides for the presentation of their research in a more interactive, less formal, venue than a conference presentation, allowing attendees to ask questions and provide suggestions to the participants. A poster session may also supplement a conference presentation by allowing a demonstration of, or hands-on access to, associated technologies, such as computer software.
Poster sessions are routine for many science departments at Colgate and are also conducted at the end of the summer research program.