Multiplying Same Bases

$${2}^{3}\cdot {2}^{4} = \left(2\cdot 2\cdot 2\right)\cdot \left(2\cdot 2\cdot 2\cdot 2\right) = {2}^{7}$$

Three 2s and four more 2s make seven 2s. When you multiply powers with the same base, add the exponents.

With letters: ${a}^{m}\cdot {a}^{n} = {a}^{m+n}$. This works for any base and any exponents. Different bases cannot be joined: ${x}^{3}\cdot {y}^{4}$ stays as it is.