Lead generation is an integral part of business because without leads, you don't have any sales. Having a regular supply of leads is especially important if your buyers aren't likely to become repeat customers. Businesses that have repeat customers often don't have to place the same importance on lead generation since each customer has a significantly higher lifetime value.

There are many different types of lead generation out there. You can create leads using email lists, opt-in forms or other strategies online. Offline, you can use the phone or take advantage of direct mail campaigns. The source I've included below goes into detail about many different types of lead generation that exist.

The bottom line is that without interested prospects, you probably won't be creating any sales. Lead generation ensures that targeted potential clients are exposed to your products or services.

Hi @renaldob!

Lead generation or lead-gen is a marketing term that refers to the creation or generation of prospective consumer interest or inquiry into a business' products or services. It is often associated with marketing activity that targets to generate sales opportunities for a company's sales force.
There are two major reasons why lead generation is part of sales.

First, marketing is passive and lead generation is proactive. Branding, lead nurturing, media ad buying, and passive conversions from existing all involve different processes and mind sets compared to outbound lead generation. Lead generation is about active pursuit of new opportunities.
Second reason why lead generation is part of sales is that its metrics are more appropriately tied to the sales process. Most of the work done by lead generation teams plays into sales instead of marketing mind sets. Other than lead source campaign ROI, none of the metrics of lead generation make any sense within a marketing-oriented process. However, marketing and sales should be aligned to target the same core markets and work together to deliver the right message to the right clients.

Sources:
http://bx.businessweek.com/lead-generation/
http://www.insidesales.com/insider/inside-sales-best-practices/lead-generation-is-part-of-the-sales-department-not-marketing/

Lead generation, or lead gen is a marketing tool used, particularly in internet marketing, to generate consumer interest or inquiry into products or services of a business. Leads can be generated for a variety of purposes - list building, e-newsletter list acquisition or for winning customers. There are many tactical methods for generating leads. These methods typically fall under the umbrella of advertising, but may also include non-paid sources such as organic search engine results or referrals from existing customers. Businesses strive to generate 'quality' leads. Quality is usually determined by the propensity of the inquirer to take the next action towards a purchase.