It's from Google. It's very easy to use: you just need to add a translation button to the tools and links bar on your browser and you'll be able to translate web pages or pieces of text with just one click. You can see the list of possible translations by clicking here: http://translate.google.com/translate_buttons?hl=es

As a translator it's limited, but it's very very easy! And Google admits as much in the following paragraph: 'Automatic translation is very complex, since the meaning of words depends on the context in which they are used. An exact translation requires a knowledge of the context and the structure and norms of a language. Despite the fact that a lot of engineers and linguists are working on it, it will be some time before anyone can offer a fast and natural automatic translation. Meanwhile, we hope the service we offer will be useful to you in most cases.'

For more information on how Google Translator works, click here.