Monitoring Effectiveness
Unless you can find out why people visit your website, you won't know which marketing campaigns have been successful or where to spend more money.
Tracking and site analysis tools
A number of suppliers sell tracking tools that can tell you where visitors come from, what they do while on your site and where they go when they leave.
If you search the internet you might come across a free trial - but bear in mind that you'll need a large amount of data for the results to be significant.
You - or whoever has access to the server hosting your website - will also be able to access a log file - a recorded history of all requests for pages on your site. It includes details of the page requested, the time and source of the request.
The problem with monitoring a log file is that it grows so quickly that you need software to glean anything useful from it. A website analysis tool is a piece of software that you can use to measure the usage patterns of your site. It does this using statistics such as the total number of visitors, the number of new and returning visitors, which search engines they are finding the site through, and which parts of the site they are making particular use of.
Some website analysis tools, such as Analog, are available free from the web. Other popular packages include Wusage and WebTrends.
User surveys
The only other way of checking how visitors reach you and whether you're providing what they want is to ask them.
Ideally, you need to know how they found the site, whether it is their first visit and why they're visiting. Pop-up surveys (new pages containing surveys that open in separate windows) are a good way of gathering this type of information - but users may simply ignore them, particularly if you ask too many questions.