At its peak, it had 80,000 members. During much of its existence it charged a startup fee of about $100 and hourly usage rates on the order of $10 per hour. It provided news sources, weather, stock quotations, a shopping service, electronic mail, various databases, online text of magazines, and airline schedules. It also had a newsgroup-like facility known as PARTICIPATE (or PARTI), which was developed by Participation Systems of Winchester, Massachusetts. PARTICIPATE provided what it called "many to many" communications, or computer conferencing, and hosted "Electures" on The Source, such as Paul Levinson's "Space: Humanizing the Universe" in the spring of 1985.
Intended for use with 300 bit/s and 1200 bit/s dial-up telephone connections, The Source was text-based for most of its existence.