General maintenance of modern computing devices can involve both the hardware and the software (I’ll include data in the software) and is an important part of owning a computer. It can be performed by the user, a designated individual in the company or family, or by a paid professional; but I will reiterate, it is important that it be done and regularly.
Hardware maintenance often consists of cleanliness; both keeping the computer and its functional peripherals clean and cleaning them when they collect dust, grime, fingerprints, etc. Many CPU units use air flow to keep cool during operation and this can lead to dust accumulation which needs to be removed periodically (6 months in some environments, yearly, or even every 2 years in very clean environments). Monitors tend to collect dust and some may build up a haze, glasses cleaner is appropriate for most, some of the early plastic screens have special requirements (check with manufacturer). Keyboards and mice can often be spruced up by inverting and removing any debris, dust, etc. If sticky stuff gets into a keyboard, it is often best to replace but normal surface cleaners may be used in an attempt to clean, again, do so with the keyboard inverted to avoid getting detergents, solvents, and so forth onto the contacts of the keys.
Software maintenance amounts to determining what needs to be updated and getting those apps updated in addition to running storage backups (your files and data) and garbage file removal before finally getting the storage drives defragmented. Some commercial software utilities will perform these tasks for you; but, at least once a month, these operations should be done manually to ensure that they complete and do what is expected of them.
Regularly: keep underside of mouse, surface of keyboard, and touch-pads clean.
Annually: check air intakes and clean if warranted. Check cooling system and clean if necessary. Remove any build up of debris or dust in the interior of the CPU case.
Monthly: perform or verify backup of important data. Remove excess files, temp files, etc. Run a defragment of all storage devices to verify error-free operation and optimize file access speed.
Weekly: verify versions for operating software (check that auto-updates are working as expected) and check on versions of security software (should never be more than 3 days old); manually update as necessary.
Example: Once a week, check that Malwarebytes is up to date and that Microsoft updates have been loading (settings, updates). Have Auslogics defrag set to run weekly and Ccleaner set to run continuously. Once a month, run Ccleaner manually to clean files and the registry; then run Auslogics defrag and have it defrag and optimize. Every six months (at the beginning of summer and winter) visually inspect the case (CPU box) and if any dust buildup is evident anywhere on the outside, open it up for cleaning or contact the person or service responsible for that service to schedule and perform a thorough cleaning.