Often, <answer>through-hole</answer> and surface-mount construction must be combined in a single assembly because some required components are available only in surface-mount packages, while others are available only in <answer>through-hole</answer> packages. Another reason to use both methods is that <answer>through-hole</answer> mounting can provide needed strength for components likely to endure physical stress, while components that are expected to go untouched will take up less space using surface-mount techniques. For further comparison, see the SMT page.
Surface-mount is one type of construction used in PCB assembly; what's the other one?
through-hole