Garota de Ipanema is the iconic bossa nova, written by Tom Jobim (music) and Vinícius de Moraes (lyrics). It conquered the world, via the US, as the The Girl from Ipanema.
The melody is part of the collective memory of mankind. Can you imagine a world without it? I can't. The secret is in the use of blue notes. These are the notes that provide colour and tension in modern harmony. In this song, the opening melody consists only of blue notes of the major chord. That makes it sound unusual, surprizing and familiar at the same time. Such is the genius of Tom Jobim.
This is one of the most covered songs in the world. Personally, I prefer it in the minimalistic João Gilberto-style. Here is my own short version.