While I still recommend the business planning process, I caution you to realize that a beautifully crafted document does not always equal business success. I've worked with many entrepreneurs who successfully launched without a plan, and some with beautifully written plans that never materialized. You and your business idea are unique. Your planning process will be unique as well. Be wary of one_size_fits_all advice or pronouncements from experts about how you should proceed.
So, although a detailed business plan may not be required for an online business, I am going to include it here so you can at least look at and consider each section and determine yourself if it applies to your business.