Period, dot or full stop

Period (ASCII 46) terminates sentences in English and serves as the decimal separator in US, UK, and most programming locales. In file systems, the dot separates filenames from extensions (report.pdf), and a leading dot hides files in Unix (.gitignore, .env). In regular expressions, an unescaped dot matches any character except newline, which is the single most common regex metacharacter surprise for beginners. DNS fully qualified domain names technically end with a trailing dot (example.com.), though it is almost always omitted in practice.