There are many classes of problems that are difficult to solve—or at least quite unwieldy algebraically—in their original representations. An integral transform "maps" an equation from its original "domain" into another domain. Manipulating and solving the equation in the target domain can be much easier than manipulation and solution in the original domain. The solution is then mapped back to the original domain with the inverse of the integral transform. Integral transforms take the form Integrate[K[t, u] f[t], {t, t1, t2}]. (See Wikipedia for details and a table of integral transforms.)