Why You Should Learn Katakana (+ 40 useful words to get you started)
Katakana is mostly used for writing loan words that originate in other languages, or names and places which do not have a kanji form. This is why katakana is so useful.
Katakana
How to Improve Your Japanese
Some common mistakes for Japanese learners and ways to best learn Japanese.
What are Hiragana and Katakana used for? Do I need to learn them?
When to use katakana and when to use hiragana, learn the difference.