Getting feedback from visitors to your website lets you know that your investment is working for you. Although even a 'passive' website could very well attract customers, we can improve on that by making sure that customers can reach you, directly or indirectly, via your Internet presence.
Perhaps the simplest way of getting some feedback is via an email link, though you won't know if the emailer saw your email on your website or elsewhere.
Another way to get feedback is to get a breakdown on who visits the website, what they look at, how often they view, etc. This can be done via 'site statistics'; these are logs of activity by visitors to your website.
A form can allow you to get specific information from potential clients. The form can be set so that certain pieces of information HAVE to be present before the form can be 'sent'; e.g. a contact telephone number . address, email may have to be given. The form can be tailored so that the potential client is given a list of options from which to choose, eg. they wish to receive a brochure, etc.
Online shopping is something that has really taken off in recent years; many businesses now make use of the Internet as both their shop window and their sales floor. Having secure hosting on secure servers and the correct software is essential for security.