Audio, Image and Video are multimedia data that are ubiquitous in the digitalrnworld. The raw forms of such data produced by capturing devices contain somernunnecessary details that can be removed so that only usable/observablerncontents are maintained for storage. Other contents are temporally or spatiallyrnredundant so that long repetitions can be represented in a more storage efficientrnway. The process of reducing the size of data is called compression. Therncompressed data are reprocessed to create the original or near original datarnthrough a process of decompression. For multimedia data, there are numerousrnalgorithms and programs to perform the compression and decompressionrnprocess that are created, developed and maintained by different commercial andrnnon-commercial organizations converting the processed data into customrnformats. The diversity in storage formats makes it difficult for users to definitivelyrnadapt a uniform standard for data management. Processing time, storagernrequirement, and bandwidth consumption of the data vary among thernrepresentations. This thesis work independently treats Audio, Image and Videorndata and carries out performance evaluation based on defined set of parameters.rnData files have been prepared and subjected to compression and decompressionrnprograms and values for the performance parameters are registered underrnuniform test environment for each data type. The observations point out therndifficulty in ultimately deciding the best algorithms in each test case due to therntrade off that exists between the defined parameters. So many real lifernapplications have been considered and optimal algorithms have been suggestedrnbased on affordable tradeoffs. A new algorithm for image compression has beenrndesigned, implemented and tested. Security test has also been done to observernthe effect of applying security features to the data. Securing data imposesrnadditional processing time and has little effect on the storage size.rnKey words: Compression, Decompression, Codec, Audio, Image, Video,rnMultimedia, Performance, Evaluation, Lossy, Lossless, Security.