A travel adapter is often treated as a universal solution to using equipment abroad. It addresses only one of several differences between electrical systems, and the others matter more.
An adapter is a mechanical fitting
A plug adapter changes the physical shape of the pins so that a plug fits a foreign socket. It does not alter anything about the electricity passing through it.
Voltage, frequency and the presence or absence of an earth connection all pass through unchanged, which is where the actual incompatibilities live.
The word adapter obscures this, since it implies conversion, and the distinction between an adapter and a converter is the one that damages equipment.
Voltage is the difference that destroys things
Mains supply around the world runs at two broad voltage bands, and a device built for the lower one will be damaged if connected to the higher.
Most modern chargers for phones, laptops and cameras handle both, and the specification is printed on the power supply itself in small text.
Devices with heating elements or motors, such as hairdryers, kettles and shavers, are the usual exceptions and are frequently single-voltage.
Frequency affects timing and motors
Supply frequency also differs between regions, and while most electronics are unaffected, anything using the mains frequency for timing or driving a simple motor may not run correctly.
Equipment can appear to work while running slower or hotter than intended, which produces failures that are not obviously connected to the power supply.
This is rarer than the voltage problem but harder to diagnose, since nothing fails immediately and the symptom is poor performance rather than damage.
Earthing is quietly removed by many adapters
Cheap adapters frequently accept an earthed plug and connect only the two live pins, leaving the earth path disconnected entirely.
For a double-insulated charger this is harmless, but for equipment that relies on an earth for safety it removes a protection the design assumed would be present.
Bathroom sockets in hotels are a separate case, often limited to shaver use and unable to supply anything drawing meaningful current.
The practical approach
Reading the input specification on each charger before packing takes a minute and answers the only question that matters for that device.
For anything single-voltage, the reliable options are to leave it at home or to use the equivalent provided at the accommodation rather than to buy a converter.
A multi-port charger built for worldwide input reduces the problem to a single adapter and a single plug, which is usually simpler than carrying a set of national fittings.