There are many facets to online marketing: banner ads, search engine optimization, social media marketing, email, and more. But without lead generation, your marketing will never be as effective as it could be. Lead generation fills your pipeline with qualified leads, giving you an interested group to utilize other marketing tactics on. It also provides a solid base to build lookalike models on: these leads have opted in because they are interested in what you have to offer, so it stands to reason that similar people would be interested, too.