For questions on the convex hull of a set, a set $X$ of points in a Euclidean space which is the smallest convex set that contains $X$. Consider adding (convex-analysis), or, for questions related to algorithms, (computational-geometry) and/or (discrete-geometry).

The convex hull of a set $X$ of points in a Euclidean space is the smallest convex set that contains $X$. They can be visualized by contracting a $n$-dimensional elastic sheet onto $X$.

Over $\mathbb{R}$ it is simply the set $[\min(X),\max(X)]$, over $\mathbb{R^2}$ it is a convex $n$-gon.