A conference with the United Kingdom (UK) on December 8, 2020, about the new UK variant, has been announced by scientists and public health experts suspecting 70% more contagious amongst all the other variants. The emergence of this variant leads to stricter safety measures in the UK. It spread in 45 countries including Denmark, Netherlands, Italy, Japan, and Australia after hitting Europe. The researchers were originally suspicious about how important the modification of D614G mutation is which appeared independently in multiple locations and was found nearly in all sequences. But the appearance of the current "UK variant", lineage B.1.1.7, has raised widespread concern, and understanding why the variants are important involves an insight into the evolution of the virus and SARS-CoV-2 genomic epidemiology. This variant caused mayhem in the UK and elsewhere in Europe within 2 weeks of its announcement. Therefore in this review, we have enclosed completely how the new variant emerged, clear explanation of the terms strain, mutation, and variant. Apart from that, the review also includes how this variant was detected, its lineage and mutations, how harmful it is, and will the approved vaccines for SARS-CoV-2 be effective against this variant with a concluding remark and future directions.