Foreign loanwords in katakana, known in Japanese as 外来語 (gairaigo), are a huge part of the lexicon, including both common words and niche jargon alike.
Many of these come from English and will be in your first Japanese lessons, like ビル (biru, building) and スーパー (sūpā, supermarket) on the ordinary end. Others are more niche but no less useful, such as アーカイブ (ākaibu, archive) or アウトソーシング (autosōshing, outsourcing). Other words come from French, like アンケート (ankēto, survey); German, アルバイト (arubaito, part-time job); and Dutch, ゴム (gomu, rubber band).
Some are simply trendy or news-related, including the words ポチる (pochiru, to purchase from an online site) or パタハラ (pata-hara, when a man suffers harassment at work for taking paternity leave).