Which one is correct?
Is it something we use in American and British English?
For the past participle and gerund corresponding to the verb age, American and Canadian writers use aging. Ageing is the preferred spelling outside North America. The dropping of the e in American and Canadian English does not extend to ageism (meaning discrimination based on age), which is the preferred spelling everywhere.
for eg.,
We need promotional campaigns to make aging seem more appealing to young people. [Los Angeles Times]
Moncton officials say the city’s underground maze of aging water pipes were a factor in this week’s water main break that forced a boil order on roughly 30,000 residents. [CBC]
Like any aging starlet, Hollywood’s annual festival of self-congratulatory excess keeps getting nipped and tucked in an attempt to remain relevant. [USA Today]
Example of “ageing”: The United Nations and the World Health Organization both using the extra “e”. See the WHO page on ageing.
