An anchor determines which point of a node is at a given position. By default, it is the center.
Syntax: \node[anchor=option] at (x,y) {Text};
Options are: center, north, south, east, west, north west, north east, south west, south east.
\begin{tikzpicture}
\node[anchor=north] at (0,0) {Center};
\node[anchor=north east] at (-5,-2) {Bottom left};
\node[anchor=south west] at (2,2) {Top right};
\draw (0,0) -- (2,2);
\draw (2,2) -- (-5,-2);
\end{tikzpicture}