If you're interested in learning more about special database lead generation, check out our article on how to structure a Lead Nurturing plan in 7 steps.
The stages of the conversion funnel are:

TOFU (Top of the Funnel): is the first contact that a potential client has with our brand or company.
MOFU (Middle of the Funnel): the user or potential customer is evaluating several purchase options.
BOFU (Bottom of the Funnel): is the moment of closing the sale.
As we said before, it is a funnel and it is called that because the first part is about reaching the largest number of potential clients. This number will be reduced as we move on to the next stage. This does not mean a loss of efficiency, but rather a natural filter that causes the most qualified users to reach the last stage of the funnel.