The best way to learn a foreign language - any language - is to learn it from infancy. Children's brains and vocal cords are wired at birth to learn language. If they hear only one language, as most do, they will learn it. If they hear two - for instance, if one parent speaks in English and the other in Spanish - they will learn them both at the same time.
Nobody knows the limit of languages that can be learned in this way by young children, but at least four or five languages can be picked up in this way by a child under the age of six or seven, if they hear them spoken. They do not seem to get confused, in general, and understand the different grammar rules intuitively.
If you have the opportunity to help your child learn two or more languages this way, please make the most of it! By the time a child is around six or seven, it becomes harder to learn a completely new language, particularly if there are sounds which are not present in language(s) they know already. The older they become, the harder it is to pick up a language merely by hearing it.
However, there are many structured ways of learning languages; ;books, CDs and online tutorials can easily be found. This site gives links to some of the free lessons online which can give a good taster. Some of these sites require registration, but this is free. Many of the sites have links to other language learning sections, too.
French
BBC French guide - there are video lessons for beginners, intermediate or advanced learners of French, worksheets, and grammar guides. You can even take a short quiz to determine what level of French you have - if any - and will be given suggestions appropriate to what you know.
French Assistant - you have to register for this site, but the lessons are free, with text and audio files to introduce French language.
French phrases - some useful words and phrases in French, to supplement early lessons and to help with communication in French-speaking countries.
Learn a Language: French - various resources for people wanting to know French vocabulary or phrases. The site also has similar resources for several other languages.
Spanish
BBC Spanish guide - as with French, there are video lessons at various levels of Spanish, worksheets and guides.
Speak Spanish - free lessons and activities, many with audio to help learn Spanish.
Spanish vocabulary - lists of some common words and phrases in Spanish, useful for expanding on beginner lessons.
German
Learn German online - ten lessons for beginners, and twenty-four for more advanced students of German.
BBC German guide - interactive lessons, worksheets and cultural information for beginners in German, and some revision for those who already know a little of the language.
German language school - the site looks basic, but there's a lot of information including useful words and phrases for learing or improving your German.
Russian
Russian lessons - extensive lessons in the language, from beginning level upwards. Grammar rules as well as vocabulary, and some audio files to hear the pronunciation.
Listen2Russian - this site requires Flash 8 or higher to be installed, and introduces Russian as it is spoken. Primarily intended for people planning to travel to Russia.
Japanese
Japanese Lessons - a thorough introduction to the Japanese alphabet and grammar
Learn Japanese - extensive lessons in the Japanese language, with reviews to check how much has been learned
Learn Japanese Adventure - beginning Japanese, with pages about simple greetings, useful words, and some grammar. Written from a personal perspective.
Greek (modern)
BBC Greek guide - video lessons, worksheets and guides to introduce some basic Greek language and culture.
Learn Greek - if you want to learn modern Greek, this is an excellent course. Registration is free, and there are 105 lessons, from beginner to advanced level. These were originally a Greek by Radio course, but now have transcriptions and discussions forums online.
Greek by the 'Thinking' method - a different way of learning Greek, via downloaded files. The first couple explain the method, and then there are a series of lesson to encourage English speakers to understand and speak simple Greek phrases, with no memorisation or rote learning.
Greek (ancient and Biblical)
Ancient Greek - set of tutorials with a lot of language/grammar drills. Read the instructions since this site is not intuitive!
Text Kit - Greek - free downloadable textbooks for Greek, both classical and Biblical, in .pdf format
Latin
Latinium podcasts - learn Latin by speaking and listening to podcast lessons. Optional small donation, with plenty of free downloads.
Text Kit - Latin - list of downloadable Latin books for various levels. All free, in .pdf format
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