Multiprogramming is the technique of running several 
programs at a time using timesharing. It allows a computer 
to do several things at the same time. Multiprogramming 
creates logical parallelism. The concept of 
multiprogramming is that the operating system keeps several 
jobs in memory simultaneously. The operating system selects 
a job from the job pool and starts executing a job, when 
that job needs to wait for any i/o operations the CPU is 
switched to another job. So the main idea here is that the 
CPU is never idle. 

Multi tasking: 
Multitasking is the logical extension of 
multiprogramming .The concept of multitasking is quite 
similar to multiprogramming but difference is that the 
switching between jobs occurs so frequently that the users 
can interact with each program while it is running. This 
concept is also known as time-sharing systems. A time-
shared operating system uses CPU scheduling and 
multiprogramming to provide each user with a small portion 
of time-shared system. 

Multi threading: 
An application typically is implemented as a separate 
process with several threads of control. In some situations 
a single application may be required to perform several 
similar tasks for example a web server accepts client 
requests for web pages, images, sound, and so forth. A busy 
web server may have several of clients concurrently 
accessing it. If the web server ran as a traditional single-
threaded process, it would be able to service only one 
client at a time. The amount of time that a client might 
have to wait for its request to be serviced could be 
enormous. So it is efficient to have one process that 
contains multiple threads to serve the same purpose. This 
approach would multithread the web-server process, the 
server would create a separate thread that would listen for 
client requests when a request was made rather than 
creating another process it would create another thread to 
service the request. To get the advantages like 
responsiveness, Resource sharing economy and utilization of 
multiprocessor architectures multithreading concept can be 
used.