Distance education focuses on teaching methods and technology to deliver instruction to students who are not physically present in a traditional classroom setting. It has been defined as a process that creates access to learning when the source of information and learners are separated by time and distance. Distance education dates back to at least 1728 when advertisements were placed seeking students for weekly lessons delivered by post. Modern distance education relied initially on developments in postal services in the 19th century and has been practiced since the 1840s. Key features of distance education include the separation of teacher and learner, separation among learners, use of one medium to deliver instruction, and use of communication channels to facilitate interaction and support for learners.