User blog comment:JapaneseOPfan/Lesson 12 or something (Pronunciation)/@comment-24568337-20150814192507/@comment-3345720-20150814193718

In some texts aimed for younger audiences (so like shonen manga), the kanji has furigana, which is basically tiny hiragana next to or above the kanji that tells you how the kanji is read. Katakana pops up rather frequently in manga though, so it might be best for you to look over that too. It's the same exact thing as hiragana, just written differently.

More mature texts (newspapers, seinen manga, official documents, etc) have less to no furigana at all, so you'll have a much harder time decoding them. You can use online radical finders like http://jisho.org/#radical to find the ones you can't read though.