Around the world, people have evolved their own conventions or practices to do things: whether it is how they number their streets or how they address each other. You don’t want to be a company singled out as a “foreigner”, who does not know their way about the local market. I18n is the way to get everything right. Some common factors are: a. Date/Time, b. Numbers, c. Currency, d. Mail address, e. Sort and search: Standardize the sort/ search for everyone, f. Hard-coded strings: Do not leave content in source code. Hard-coded strings should be externalized to a resource file and keys should be used in the code to avoid these issues., g. Unicode or double-byte or multi-byte character support, h. Bi-disupport or right-to-left support, i. Embedding text in image: This is a strict no-no, just as placing content in the source code is., j. GUI elements: All languages may not take up the same amount of space, whether be it because of the size of their characters or because of word length. For example, German may take up to 40% more space than English. In Indian languages, there are combination characters and these sometimes break up in the graphic user interface (GUI).The Thai language does not have separators or word delimiters.
Getting date, time, number, and mail address formats right may not sound like a big deal, but imagine an e-commerce website not being able to deliver goods to its customers, because it did not record their addresses right. Many a time, if your forms are not internationalized, the customer may not even be able to place the order. Or, if your products display their prices in the wrong formats, they may be thought to have outlandishly high prices or deemed to be too cheap, depending on which decimal indicator is used.
Your i18n manager must be able to take care of all such and other issues that may be specific to different languages.