i18n and L10N

i18n and L10N are more difficult than I image. After some research, I understand more why it is hard.

W3C defines i18n and L10N as below.

Internationalization is the design and development of a product, application or document content that enables easy localization for target audiences that vary in culture, region, or language.

Localization refers to the adaptation of a product, application or document content to meet the language, cultural and other requirements of a specific target market (a locale).

wikipedia also has explanation about them and list out their scope. 

Internationalization is the process of designing a software application so that it can be adapted to various languages and regions without engineering changes. 

Localization is the process of adapting internationalized software for a specific region or language by adding locale-specific components and translating text. 

Sometimes g12n (globalization) means the process of i18n + L10N.

During i18n and L10N process, we also need understand Locale, Language, Timezone.

Locale settings control how numbers, dates, and times, Currency, Measurement units display for your region - which may be a country, or a portion of country or may not even honor country boundaries.
The locale settings are about formatting output given a locale.
A locale, on the other hand, is a specific international market where a target user is working. A locale encompasses many of the issues discussed earlier when I defined localization: the conventions, culture, language, and preferences of typical users in the environment. This includes issues that are crucial to applications, such as number, currency, date/time formats, and date/time separators. 

Language, on the other hand, is what we speak, read, and write. Language settings control in what language text appears independently of the locale settings.

Language is a term that just about everybody is familiar with; it is a grouping of sounds and symbols that are organized into combinations and patterns S that enable people to communicate. 
 
Most of the time zones on land are offset from Coordinated Universal Time (UTC) by a whole number of hours (UTC−12 to UTC+14), but a few are offset by 30 or 45 minutes (for example: Nepal Standard Time, NPT). Some higher latitude countries use daylight saving time for part of the year, typically by changing clocks by an hour.