It is the share of time your site is available. 99.99% means no more than about 4–5 minutes of downtime a month. For a business, customers almost never see an error instead of your site.
What to prepare
Briefly describe your project, current platform, goal and deadline, and leave one convenient contact. Do not send passwords, documents or confidential material through the public form.
How to move forward
Explore the relevant service or ask a question in the chat. For a practical estimate, submit an enquiry for the team to review.