It is important to take localization and translation into consideration from the beginning as it can become difficult and costly to apply it later. Fortunately, the platform can do a lot of work for you.
Localization and translation
Localization
When using the native user interface, it automatically formats the values of numeric and date fields according to the Locale field on the user profile. Visualforce pages using the apex:outputField and apex:inputField components will automatically format values, and outputting local sensitive values in any other way will need to be handled manually in your Apex controller code or in your JavaScript code. Lightning components using lightning:outputField and lightning:inputField...