How do you bind classes and styles dynamically in Vue?

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Vue gives `:class` and `:style` special **object and array syntax** so you can conditionally apply classes and inline styles based on reactive state — cleaner than building class strings manually. ## Object syntax for :class — toggle classes by condition ```vue ``` Each key is a class name and each value is a boolean condition — the class appears only when its value is truthy. This is the most common pattern for state-driven styling (active tabs, error states, etc.). ## Array syntax for :class — combine multiple ```vue ``` ## :class merges with the static class attribute ```vue

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``` You can use both `class` and `:class` together; Vue merges them. ## Object/array syntax for :style ```vue ``` ## Binding classes on components ```vue ``` ## Why it matters Dynamic class/style binding is everyday Vue work — highlighting the active nav item, showing validation errors, theming. The object syntax (`{ className: condition }`) makes conditional styling declarative and readable, avoiding error-prone manual string concatenation. Knowing that `:class` merges with static `class`, and the array form for combining sources, covers virtually all conditional-styling needs cleanly.