With more than 16,000 stocks listed in the US, it’s difficult to discover a winning stock amid the market’s clutter. Fortunately, stock screeners greatly simplify that process and allow investors to generate a steady stream of investment ideas.

To help our readers make the most effective use of stock screeners, we’re initiating a three-part series to describe the process of building a custom stock screen. In this article, we’ll examine three of the most popular online screening tools. Over the following two months, we’ll discuss how to build screens that focus on growth and value plays.

The Internet offers a number of free stock screening services, as well as some that charge monthly or annual subscription fees. In addition, brokerage firms often provide stock screeners on their websites at no additional cost.

Google Finance offers a basic screening service that allows users to screen a universe of about 6,500 stocks against 60 fundamental data points. Those data points include measures of growth, margins, leverage, five- and 10-year returns on investment, assets and equity—all of which are essential to build basic growth and value screens. Unfortunately, Google Finance’s screener doesn’t allow users to save the custom screens they’ve created, though users with a free Google account can build a watch list of securities that fulfill their screening criteria.

Despite its shortcomings, Google Finance’s screener is an excellent way for new investors to familiarize themselves with the screening process.

Yahoo! Finance’s screener allows users to screen with more criteria than Google Finance, but it offers no historical data and its coverage universe is smaller. That lack of historical data is a significant drawback because it’s difficult to develop value screens without a company’s longer-term fundamental data points. Although Yahoo! Finance doesn’t offer nearly as much data as Google Finance, its service does enable users with a free Yahoo! account to save their custom screens for future use and build watch lists.

Morningstar offers two versions of its screening service, both of which require an account with the company.

Its free screener is limited to just 18 fundamental criteria, three of which are proprietary to Morning-star. And like Google Finance’s service, users can create a watch list, but they can’t save any screens they’ve created.

Morningstar’s Premium Stock Screener is the most robust of the services available. The Premium Stock Screener has almost 500 screening criteria available, with between five- and 10-years’ worth of historical data available for most criteria.

Its screening criteria include growth and valuation metrics, extensive financial information and analyst estimates. And the service allows users to save their custom screens for use in the future.

The only drawback to the Premium Stock Screener is its expense; an annual membership to Morning-star currently costs $185 per year.

Although there are numerous stock screeners available on the Internet, these three screeners offer the easiest way for investors to begin building their own stock screens.