Tipping generates more anxiety among travellers than almost any other practical matter, and most of the confusion comes from not knowing what the practice is compensating for.

The wage structure explains most of it

The underlying variable.

Where tipping is expected and substantial, service staff wages are frequently structured on the assumption that tips form a significant part of income, and the base rate reflects that.

Where tipping is minimal or absent, wages are generally set at a level intended to be complete, and service charges where they exist are distributed by the employer.

Which means the same gesture has different meanings. In one system it is a substantial part of somebody's income; in another it is a bonus on top of a full wage.

Understanding which system you are in resolves most of the uncertainty.

The broad patterns

Stated generally, since specifics change and vary by city.

In some countries, tipping in restaurants at a substantial percentage is standard and expected, and not doing so is a meaningful statement.

In much of continental Europe, service is frequently included and rounding up or leaving a small amount is customary rather than obligatory.

In parts of East Asia, tipping is uncommon and in some contexts is actively unwelcome, being perceived as implying the wage is inadequate.

And in many places practice differs between contexts — a taxi, a hotel, a restaurant and a bar may each have different conventions in the same city.

The service charge question

Where the most confusion arises.

A service charge added to a bill may be distributed to staff, retained by the business, or partially both, and practice differs by jurisdiction and by establishment.

Several jurisdictions have legislated to require service charges to be passed to staff, following evidence that they frequently were not.

Which means a service charge on a bill does not necessarily mean staff have been paid, and asking is reasonable where it matters.

Where a service charge is included and passed on, an additional tip is generally not expected.

The tipped occupations beyond restaurants

Worth knowing since they are less obvious.

Hotel housekeeping, which is among the most commonly overlooked, is customary in some countries and not in others.

Porters, doormen and concierge staff, generally per service rather than as a percentage.

Taxi and rideshare drivers, with substantial variation by country.

Guides and drivers on tours, where the convention is frequently stated by the operator and where the amounts can be substantial over a multi-day trip.

And personal services — hairdressing, spa treatments — which follow local restaurant conventions loosely.

Digital prompts and the expansion

A recent development worth addressing since it has changed the experience.

Payment terminals increasingly prompt for a tip in contexts where tipping was not previously customary, including counter service and retail.

The prompts are frequently presented with high default options, and the social pressure of a prompt in front of the person serving you is a deliberate design.

Surveys have reported growing resentment about this, which is directed at the prompts rather than at the staff, and the reasonable position is that declining a prompt in a context where tipping is not customary is not a discourtesy.

How to find out what is expected

Practically, rather than guessing.

Guidance published by tourism authorities and by reputable guides is generally accurate on the broad convention.

Asking accommodation staff on arrival, who answer this frequently and know local practice.

Observing what other people do, which works in restaurants and less well elsewhere.

And for tours and guided activities, asking the operator directly, since they have a view and it removes the awkwardness entirely.

The reasonable position

Tip according to local convention rather than to the convention you are used to, in either direction.

Over-tipping in a low-tipping culture is not generosity so much as a failure to observe, and it can create awkwardness.

Under-tipping in a high-tipping culture has a direct cost to somebody whose income depends on it, which is the situation where getting it right actually matters.

And carrying small notes, which is the practical constraint that most often prevents people from tipping when they intended to.

Currency and small amounts

The practical obstacle that most often prevents tipping appropriately.

Card payments frequently do not accommodate tips in some countries, or route them in ways that do not reach staff.

Carrying small denomination notes is the reliable method and requires deliberately obtaining them, since cash machines dispense large notes.

Breaking notes early in a trip, at a shop or a cafe, is worth doing on the first day.

And leaving foreign currency that cannot be exchanged is not a tip, which is worth remembering at the end of a trip.

Group and large party charges

A specific arrangement worth knowing.

Restaurants commonly add an automatic service charge for parties above a stated size, which is disclosed on the menu and frequently missed.

Where it has been added, an additional tip is not expected, and paying twice is a common and avoidable error.

Checking the bill before adding anything is the whole of the remedy, and it is worth doing generally since automatic charges appear in more contexts than they used to.