1. Connections: The Relay Chain
Having a blockchain is fantastic, but it will be limited in its applicability for most businesses until it can reach out to the larger blockchain community. To achieve this securely and efficiently on its own, a blockchain project would need to establish extensive infrastructure, and many initiatives have failed because they were unable to provide the necessary seamless connectivity.
2. Empowering Construction: Substrate
Substrate, a very powerful tool provided by the Polkadot framework, significantly simplifies the process of creating a blockchain from scratch. It is designed to assist teams in building the exact blockchain they require, and it includes protocol connection points that connect to the relay chain features.
This has two major advantages: it allows teams to focus less on building the foundation for yet another blockchain project and more on the added value of their product.
3. Security and Speed: Host Platform
Once blockchain projects, known as parachains because Polkadot processes transactions from all chains in parallel, are on the relay chain and operational, they can reap one of the most significant benefits: using Polkadot's established security and fast and scalable transaction speeds.
4. Connecting to the World: Bridges
Polkadot's network is designed to act as a relay between the parachains. It does, however, include bridges to the Ethereum and Bitcoin networks, allowing parachains to access and interact with a large network of systems without having to choose which network has the best connections for them. Polkadot does not compete in this sense with top networks like Ethereum, but rather competes for users while cooperating and delivering value to individuals on both sides.

https://polkadot.network