Glossary: Kotlin Basics

collection functions (filter, map, sumOf, etc.)

Also written: filter, map function, sumOf, count, any, all, firstOrNull, sortedBy, maxByOrNull, joinToString, forEach

Functions on collections that take a lambda and apply it to each item. `filter` keeps matching items, `map` transforms each item, and `sumOf` totals them. They return new values and don't change the original.