Susumu Ohno introduced the term, junk DNA, in 1972. Junk DNA represents the genome sequence portions that have no discernible function. Scientists maintain that junk DNA does not convey any selective advantage to organisms and does not possess any specificity. However, researches indicate that certain junk DNA sequences can have functional activity that is difficult to identify or certain other junk DNA sequences could have functional activity in the past. Junk DNA is also termed as non-coding DNA. This DNA does not produce proteins. Junk DNA makes up around 98% of human genome. Recent researches establish that junk DNA plays a significant role in human lives, even if it is not having functional activity. Changes in junk DNA leads to structural changes in the genome, with nearby active DNA molecules getting impacted. It is a very complex process and mutations related to diseases are controlled from even substantial distances. Further, emerging evidences reveal that the vast stretches of junk DNA in humans play crucial roles in evolution. Hence, scientists believe that unraveling the secret of non-coding DNA can show why people are different and how humans possess the ability to adapt quickly and remain flexible.