The 3rd International Conference on Data, Engineering and Applications 2021 (IDEA-2k21)is being organized during Oct 08-09, 2021 in Bhopal (The city of Lakes), India. IDEA-2k21 is the premier forum for the presentation of new advances and research results in the fields of Big Data, Data Mining, Machine Learning, Data Science and their associated learning systems and applications. The conference will bring together leading academician, scientists, expert from industry and researchers in the domain of interest from around the world. The Keynote talks will be delivered by Internationally renowned experts. Contributions from researchers describing their original, unpublished, research contribution which is not currently under review by another conference or journal and addressing state-of-the-art research are invited to share their work in all areas of Big Data, Data Mining, Machine Learning, Data Science and their associated learning systems and applications.The full length paper(12-15 pages) of high quality should be submitted using Easy Chair . The post-conference proceedings of IEEE 2nd IDEA-2k20(28-29 Feb 2020, Bhopal) is published by IEEE Explorer. The post-conference proceedings of Springer 1st IDEA-2k17(28-29 Oct 2017, Bhopal) is published by Springer in two volumes Data Engineering and Application Vol-I and Data Engineering and Application Vol-II