A website's welcome message should describe what the website offers its visitors. For example, "Reddit's stories are created by its users." The welcome message can be either a statement of purpose or brief extracts from the most-important pages.
Use the website's important keywords in the welcome message. Keep the welcome message brief and concise, and ensure it tells users what they can find and achieve on the website in as few words as possible. Use simple terms, and make the message user-centric.
Another example includes "KarmaTube is dedicated to bringing inspirational stories to light, using the power of video and the Internet to multiply acts of kindness, beauty and generosity."