Digital images are required to store a large among of storage space in digital computers. Nowadays, computer system is very capable to process digital images with high resolution quite easily. The transmission of huge data needs more time to transfer over network channel. Thus, time and space are two fundamental components of computing. In the field of digital image processing, image compression is one of the most popular and commercially successful technologies, which compressed the size of data according to express a given quality of information. In addition to, digital images store three type of information such as redundant, useful and irrelevant. In this paper, various compression techniques have been discussed. Image compression techniques are divided into two categories such as lossless and lossy image compression. Both techniques have been discussed with suitable examples and block diagrams.