Pseudolocalization is a process of localizing text to fake languages to test how applications handle localization. It helps test spacing for longer translated text, catch untranslated text, and test user interface behavior with bidirectional text like Arabic. Some common pseudolocalization techniques include adding accents to words, increasing word lengths, adding brackets around words, and using emojis. Pseudolocalization works at the translation layer but can be combined with styling when viewing in test mode. Fake locale names can use reserved namespaces like en-x-pseudoaccented or made up names like en-pseudoaccented that are unlikely to conflict with real locales.