While demonstratively chewing gum or playing music loudly at the back of the bus are almost universally frowned upon, other areas of our modern lives lack the clear-cut rules of the Downton Abbey era.
Etiquette experts Debrett's have apparently been inundated with anxious requests from members of the public asking them to clear up the Ps and Qs of the smartphone age.
Debrett's editor Jo Bryant spoke to Good Morning Britain about the pitfalls of modern behaviour and how technology is creating a new set of etiquette challenges.
The magazine received 10,000 different queries in the past year, many of which have gone into its latest Debrett's Handbook, a 480-page guide to modern manners.
Some of the common dilemmas they received are classics, while others are a bit more new-fangled:
Is it OK to apply make-up on public transport?
No, unless it is an emergency touch-up this should be avoided.
Can I use my phone when transacting business?
It is rude to pay more attention to your phone than a person, and they should always be put away when transacting other business
Can I put my seat back on the plane?
According to Debretts, it's selfish to recline your seat back during short daytime flights. Hogging the arm-rest should also be avoided.
Can I smoke an e-cigarette in the office?
Absolutley not. 'Vaping; shows that you are not focused on your work and may also be a distraction to colleagues.