First, I would like to thank a few people from Packt Publishing: Kevin for encouraging me to write this book, Prachi for assisting and guiding me throughout the writing process, Pankaj for helping me out in technical editing, and all other contributors to this book.

I would like to thank all the developers, contributors, and forums of Hadoop, HBase, and Big Data technologies for giving the industry such awesome technologies and contributing to it continuously. Thanks to Lars and Noll for their contribution towards HBase and Hadoop, respectively.

I would like to thank some people who helped me to learn from life, including teachers at my college—Roshani ma'am (Principal), Namboothari sir, Santosh sir, Manjush ma'am, Hudlin Leo ma'am, and my seniors Jitesh sir, Nilanchal sir, Vaidhath sir, Jwala sir, Ashutosh sir, Anzar sir, Kishor sir, and all my friends in Batch 6. I dedicate this book to my friend, Nikhil, who is not in this world now. Special thanks to Ratnakar Mishra and Chandan Jha for always being with me and believing in me. Thanks also go out to Vineet, Shashi bhai, Shailesh, Rajeev, Pintu, Darshna, Priya, Amit, Manzar, Sunil, Ashok bhai, Pradeep, Arshad, Sujith, Vinay, Rachana, Ashwathi, Rinku, Pheona, Lizbeth, Arun, Kalesh, Chitra, Fatima, Rajesh, Jasmin, and all my friends from C-DAC Trivendrum college. I thank all my juniors, seniors, and friends in college. Thanks to all my colleagues at C-DAC Cyber Forensic: Sateesh sir, my project manager; Anwer Reyaz. J, an enthusiast who is always encouraging; Bibin bhai sahab; Ramani sir; Potty sir; Bhadran sir; Thomas sir; Satish sir; Nabeel sir; Balan sir; Abhin sir; and others. I would also like to thank Mani sir; Raja sir; my friends and teammates: Maruthi Kiran, Chethan, Alok, Tariq, Sujatha, Bhagya, and Mukesh; Sri Gopal sir, my team leader; and all my other colleagues from PointCross. I thank Ramesh Krishnan sir, Manoj sir, Vinod sir, Nand Kishor sir, and my teammates Varun bhai sahab, Preeti Gupta, Kuldeep bhai sahab, and all my colleagues at HCL Infosystems Ltd. and UIDAI. I would also like to thank Satish sir; Sudipta sir; my manager, Atul sir; Pradeep; Nikhil; Mohit; Brijesh; Kranth; Ashish Chopara; Sudhir; and all my colleagues at Cognilytics, Inc.

Last but not the least, I would like to thank papa, Dr. Rameshwar Dwivedi; mummy, Smt. Rewa Dwivedi; bhai, Vishwas Priambud; sister-in-law, Ragini Dwivedi; sweet sister, Bhumika; brother-in-law, Chandramauli Dwivedi; and new members of my family, Vasu and Atmana.

If I missed any names, it does not mean that I am not thankful to them, they all are in my heart and I am thankful to everyone who has come in my life and left their mark. Also, thanking is not in any order.