There are three sets of alphabets in Japanese: Kanji, Hiragana and Katakana. Many nouns are written in Kanji, verbs and adjectives are written mostly in Kanji-Hiragana combination, particles and auxiliary verbs are in Hiragana, and words borrowed from foreign languages in Katakana.
Kanji are ideograms brought from China.
Each Kanji has a meaning. So we can guess the meaning of Kanji words in sentences even if we can’t read the word. And, since there are thousands of homonyms (words that are pronounced the same way) in Japanese, Kanji help to avoid confusion.
Hiragana and Katakana were made by simplifying Kanji.
Today, we use Katakana mostly to express words from other countries or when to emphasize something, simliar to how capital letters are used in English.
Today, Japanese people tend to use Katakana a lot in their conversations, even in newspapers. Some Japanese people think all words written using Katakana come from English. Of course, there are Katakana words from English like コーヒー [co-hi-] (coffee), ジュース [ju-su] (juice), etc… But actually Katakana words come from many languages. Although they don’t necessarily have the same meaning and pronunciation.
I will show you some imported words.
Pan → パン（bread）
Carta →カルタ（Japanese card games）
Orgel →オルゴール（music box）
Ransel →ランドセル（school bag for elementary school）
Decken →ゼッケン（racing number）
Gelande →ゲレンデ（ski run）
Piment →ピーマン（green pepper）
Ikraa →イクラ（salmon roe）
Kampaniya →カンパ（fund-raising campaign）
and so on…..
There are more imported words from other languages like Chinese, Spanish, Italian etc. and more imported words are being introduced into the Japanese language everyday.
I think that our language and our environment, including culture and society are inseparable. That means that if the language is changed by its user, the environment is also changed; just as we have started using Katakana a lot with Globalization. I think that we can understand many things by being aware of shifts in language.