Every record in a workflow is either a company or a person. Most steps work on one type, so the type flowing at each point decides which steps you can add next. This is why the builder greys some steps out.
Where the type comes from
The type is set by your sourcing step or your trigger:
Companies: Segment TAM, Companies search, Company lookalike, and the company event triggers (Deal closed, Deal created, Account created, Account added) all start with companies.
People: People search, People lookalike, and the people event triggers (Contact created, Contact added) start with people.
Switching from companies to people
One step changes the type: Extract people from companies. It takes companies in and produces the people found at each. Everything after it works on people.
There's no step that turns people back into companies — plan the order so the switch happens where you need it.
Which steps accept which
Company steps: Segment & score, Fetch website, Send companies to CRM. (Segment TAM, Companies search, and Company lookalike produce companies.)
People steps: Enrich, Send people to CRM, Send to sequencer. (People search, People lookalike, and Extract people from companies produce people.)
Either type: AI research, Google search, Website similarity, Route, Branch, Filter, Wait, Aggregate, Notify, Export to CSV, HTTP request.
Why a step is greyed out
If a step is greyed out in Add a step, it doesn't accept the type flowing at that point. For example, Enrich (people only) won't be offered in a company workflow until you've added an Extract people from companies step. The picker shows the reason on hover, and groups incompatible steps under an Incompatible header.