Most online courses are designed to accommodate a student's busy schedule. Students are expected to complete weekly assignments and take tests as scheduled. Class sessions can be either synchronous or asynchronous or a combination of both. Individual professors decide how their course will be delivered. Communication between students and faculty can occur during the live class session in a discussion window and outside of class via email, threaded discussion groups and by telephone.
Many courses utilize audio and videostreaming class lectures.
Some students report this is very similar to attending the class live in person. It depends which program you decide to complete. Certificates can be completed in two years or less. Degree completion programs can take as much as four years or more to complete. It really depends on how many courses you take each semester.