What is the name of the $\in$ symbol and where does it come from? It looks like a lower-case epsilon, but the Wikipedia page on epsilon states that they are not the same. Does this symbol have a typographic identification outside of mathematics? Where did the symbol come from?

This is the **membership relation** , but in set theory this is also known as **the epsilon relation** , and historically the notation was indeed $\varepsilon$.

(For example, I have the book from 1948 by Tarski and Jonsson _Cardinal Algebras_ where such notation is employed.)

According to this page it was Peano who used epsilon. I suppose somewhere around the 1960's or so, when typography was easier to modify the symbol was taking the modern shape of $\in$ (Bourbaki in their set theory book, ca. 1970, were using $\in$).