Modern electronic data capture software is typically web-based and utilizes a thin client. Web-based means that the software runs entirely on a Web server (think Google.com), and thin client means that the only tool you need is an ordinary web browser (without any cumbersome plug-ins) connected to the internet in order to access and utilize the EDC software (again, think Google.com).
Clinical trial data may be captured electronically at its source (called e-source), or in paper form and later transcribed into the EDC system.