# About Linking in MathML

You can create and use links in mathematical expressions. These links are represented using a draft version of the XML Linking Language (XLink). Only simple unidirectional hyperlinks are available, but you can associate a link with any part of a formula. For example, the fraction in the formula below is a link to the W3C home page:

y = 1 x 2 + 1

Double-clicking any character within the fraction loads the W3C home page.

To create such a link, select a math expression (the fraction in the above example), click the Link button (or choose Create or change link from the Links menu), and click the desired target.

If the target is an expression in a formula, you must first turn the expression into a target. Select the expression and choose Create target from the Links menu to create an `id` attribute for the target expression.