How does a buffer overflow attack occur?

For the toolbar, press ALT$+$F$10($PC$)$ or ALT$+$FN$+$F$10($Mac$).$

$\backslash$table$[[$B I,$u_f,$Paragraph,$,,,v,10$pt$,,v,,$:$,A^2,1vv,I_x,$& $],[\frac{?}{\text{b}\text{a}\text{r}}(),x^2,8,,{}_k,-+-,,v,,,in,,,,,!]]$