Computer assisted instruction (CAI) is the most commonly used and the most frequently researched kind of educational computer use. The computer assisted instruction (CAI)  is an interactive instructional method that uses a computer to present materials, track learning and direct a user to additional materials, which meet the student's needs. It can also be used to describe the Internet based instruction through the use of WebPages, web bulletin boards and newsgroups, video and real audio, graphics and hands-on applications. It is especially useful in distance learning situations. The explosion of the Internet and the demand for distance learning has generated a great interest and an expansion of the Computer assisted instruction. 

There are numerous unique features of the CAI, which make it an exciting field. Before the dominance of the microcomputers, distance learning was mainly accomplished through PI or the US mail system and supplemented by a telephone contact. Today, on the contrary, the CAI distance learning provides a regular and timely interaction with an instructor and a current feedback. Students can repeat tutorials as often as needed and work at their own pace. The CAI also can be used with greater numbers of students than a traditional classroom would hold. The CAI and web-based instruction have opened avenues of access to individuals with disabilities that were not possible before.
The use of the CAI as a supplement to a conventional instruction produces a higher achievement than the use of the conventional instruction alone. Students learn material faster; retain what they have learned better with the CAI than with the conventional instruction alone. The use of the CAI leads to more positive attitudes toward computers, course content, a quality of instruction, a school in general and self-as-learner than the use of the conventional instruction alone. The following is a list of reasons given by students for liking the CAI activities and/or favoring them over traditional learning. These student preferences also contribute to our understanding of why the CAI enhances the achievement.
Students say they like working with computers because computers:
• Are infinitely patient
• Never get frustrated or angry
• Individualize learning
• Are self-paced
• Do not embarrass students, who make mistakes
• Make it possible to experiment with different options
• Give an immediate feedback
• Are more objective than teachers

The web-based instruction is unique, since the students and/or instructors can communicate with each other anywhere in the world within seconds via the Internet. The feedback from the instructor can be obtained immediately.
The advantages of the Computer assisted instruction include flexibility for students so that they can work at their own speed at the time that is the best for them. With the web-based instruction, they can work at home, at school or anywhere; there is always a computer with an Internet connection. The CIA distance learning allows students with handicaps or learning disabilities to learn in a less restrictive environment. Additionally, the students, who enroll in courses via the CAI, including web-based classes, gain an opportunity to learn computer skills, which benefit them in many aspects of their lives.