It depends on the type of wood and how you want it to look. If you have a wooden deck, it's important to keep it in good condition by sealing it every few years. Deck sealers come in two types: water-based and oil-based. Water-based sealers are easier to apply and less likely to cause problems with the wood, but they don't last as long as oil-based sealers. Oil-based sealers are more durable, but they're harder to apply and can be harmful to the environment. The best way to decide which type of sealer is right for your deck is to read the label carefully and follow the instructions.

That depends on your goals for the deck. Staining will protect the wood and give it a richer color, while water sealing will help to prevent rot and decay.