How do asynchronous online courses differ from synchronous online courses?

In the context of distance learning, the primary difference between asynchronous and synchronous courses lies in their scheduling and interaction requirements:

• Asynchronous courses: These are designed to remove time constraints, allowing students to access materials and participate in course features at their own convenience. Common tools include e-mail, threaded discussion forums, and recorded content like podcasts that can be viewed or listened to at the student's leisure.1
• Synchronous courses: These require participants to be present at the same time. They utilize technologies such as live video, audio, and shared access to electronic documents during scheduled sessions, simulating a real-time classroom environment.1

While many modern web-based courses are primarily asynchronous to provide greater flexibility, both formats are often integrated into course-management systems to facilitate communication between instructors and students.1