Rainwear is made with different levels of waterproof capabilities.  Along with how waterproof a jacket, is its breathability.  Jackets may be waterproof and breathable, water-resistant and breathable aor waterproof and non-breathable.  Waterproof and breathable jackets keep rain out of your jacket while letting your sweat evaporate out the fabric, thus keeping you dry.  Water-resistant and breathable jackets repel some rainwater, but not as much as a waterproof jacket.  These jackets are more breathable, allowing more sweat to escape out the jacket.  These are best purchased for highly active uses.  Waterproof non-breathable jackets are heavily coated, so no rainwater penetrates the jacket.  As a trade-off, these jackets are not breathable and best used for standing in the rain with little movement.  Often, these jackets are vented to help the jacket breathe and allow some of your sweat to escape.