Simply put, your brand is your promise to your customer. It tells them what they can expect from your products and services, and it differentiates your offering from your competitors'. Your brand is derived from who you are, who you want to be and who people perceive you to be.
Are you the innovative maverick in your industry? Or the experienced, reliable one? Is your product the high-cost, high-quality option, or the low-cost, high-value option? You can't be both, and you can't be all things to all people. Who you are should be based to some extent on who your target customers want and need you to be.
The foundation of your brand is your logo. Your website, packaging and promotional materials--all of which should integrate your logo--communicate your brand.