How are foreign words written in Japanese?

There are three main ways to write foreign words in Japanese:

1. Katakana: This is the most common way to write foreign words. Katakana is a syllabary, meaning that each character represents a syllable. Foreign words are typically written in katakana based on their pronunciation in the original language. For example, the English word "computer" is written as "コンピュータ" (kompyuuta) in katakana.
2. Romaji: Romaji is the Japanese pronunciation of the Roman alphabet. It is sometimes used to write foreign words that are difficult to write in katakana, such as words with non-Japanese sounds. For example, the English word "rhythm" is often written as "リズム" (rizumu) in romaji.
3. Kanji: Kanji are Chinese characters that have been adopted into the Japanese writing system. Some kanji have readings that are similar to foreign words, so they can be used to write those words. For example, the English word "university" is often written as "大学" (daigaku) in kanji.

In addition to these three main ways, there are a number of other ways to write foreign words in Japanese. For example, foreign words can be transliterated into hiragana, or they can be written using a combination of katakana, hiragana, and kanji.