The 21st (twenty-first) century is the current century of the Anno Domini era or Common Era, in accordance with the Gregorian calendar. It began on January 1, 2001, and will end on December 31, 2100. It is the first century of the 3rd millennium. It is distinct from the century known as the 2000s which began on January 1, 2000, and will end on December 31, 2099.
The first years of the 21st century were marked by the rise of a global economy and Third World consumerism, mistrust in government, deepening global concern over terrorism and an increase in private enterprise. Effects of global warming and rising sea levels continued, with eight islands disappearing between 2007 and 2014. The Arab Spring of the early 2010s led to mixed outcomes in the Arab world. While most member states of the European Union introduced a common currency, the Euro, the United Kingdom voted in a referendum to leave the European Union: Brexit. The Third Industrial Revolution which began around the 1980s also continues into the present, and is expected to transition into Industry 4.0 and the Fourth Industrial Revolution by as early as 2030. Due to the proliferation of mobile devices, more than half of the world's population have access to the internet (2018 estimate), allowing humans to be more interconnected than ever before. DNA sequencing cost continued to fall: the first human genome cost three billion dollars; in 2018, sequencing one human genome cost about $1000.