This practice is mostly useful in the context of a Translation crowdsourcing where the content to be translated can be broken down into very short chunks (ex: single sentences) that can be translated independently of one another.
In the context of a volunteer-based Translation crowdsourcing initiative, recruiting and motivating motivate and recruit translators is one of the most challenging issues.
While there may be a few people in the world who might be willing to invest many hours to translate your content, there will be a lot more people who, while sympathetic to your cause, may not be willing might be willing to invest that much time.
Therefore, make it possible for a very large number of people to translate very small chunks (ex: one sentence) of your content, in a "playful, casual" fashion. Another possibility is to allow users to vote on competing translations for a same small chunk.
For example, if the content to be translated is related to a particular web site or software application, you might display a not-too-distracting popup on the side, which asks the users to translate a sentence or a term related to what he is currently seeing on the screen.
The user interface should be designed to give the user the feeling of a very casual, one-off contribution. Sort of like pulling loose change out of your pocket and putting it in a Salvation Army Kettle at Christmas time. The user should be able to easily opt-out of seeing those popups (or the popups should only show up when the user explicitly opted-in).
Links to related patterns
- This practice is one of many ways to Support Variable Levels of Involvment
- Facebook users can opt-in to translate content in that way.