Greater-than or equal to

x ≥ 18 includes 18 itself, which is the difference between ≥ and plain >. The parts of the sign arrived at different times: > comes from Thomas Harriot’s algebra, published after his death in 1631, while the bars meaning “or equal” were added in the following century, most notably by Pierre Bouguer in 1734, who drew two of them beneath the sign.