The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information.The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years. Cell culture is the complex process by which the cells are grown under controlled conditions. A consistent presence of floating cells is a common phenomenon in cultures of human embryonic stem cells (hESCs). It is currently believed that unavoidable imperfections in culture conditions lead the cells to undergo senescence and apoptosis resulting in unattached cells floating in the culture medium. Inspired by recent studies on mitotic activities in human embryonic stem cell colonies, we believe the existence of floating cells is not simply the result of unfavorable growth conditions but an intrinsic phenomenon resulted from maintaining the pluripotency of hESCs under the culture conditions. Continuous cell division across the colonies is responsible for the emergence of floating cells during hESC culture. This is quite different from the bacterial colony growth where the cells in the center of colonies are quiescent. Results indicates that continuous cell division, even at the costof floating cells formation, is essential for human embryonic stem cell proliferation.(Chen L, Jin Q, Gong Jand Krishna Dasa SS, The Nature of Floating Cells in Human Embryonic Stem Cell Culture)