Rosalind (named after Rosalind Franklin, the scientist whose work established the structure of DNA) is an education site aimed to freely teach anyone bioinformatics.
The language Rosalind uses is Python and may be a setback for those without programming experience as it assumes the user is acquainted with Python. However, anyone experienced in other computing languages such as Java can pick up Python with relative ease. For those who would like to learn Python, there are many online tutorials.
In addition to teaching bioinformatics, the website also has instructional problems on computational algorithms and understanding bioinformatics website such as GenBank.
Although the primary language of the website is Python, I like to practice my other computing languages — particularly Java and Perl.
rosalind.info is the official Rosalind website
python.org is the official Python site
learnpython.org is an online tutorial to learning python (does not require prior programming experience)