Any algebraic curve in projective $3$-space that is not contained in a plane has degree at least $3$ -- that is, it meets any plane in at least 3 points. Moreover, any curve of degree $3$, can be parametrised (in suitable coordinates) by \vskip .1in $t--> (t, t^2, t^3)$ \vskip .1in \noindent This was known 150 years ago, and since that time many mathematicians have used and generalized the result. I will describe some of the ideas involved, including recent work of mine with Mark Green, Klaus Hulek and Sorin Popescu.