At what point should a html form be split into several pages? Are people put off by long forms or is it best to have the whole thing on one page?
It is best to have short and to the point forms. Collect the information that is required. You should put yourself in the user's shoes and see if the form is too long. It is recommended to split the form and use a progress indicator something like a Step X of Y thing. Also, group similar fields on the same page and only ask what you'll really use.
I think the best rule is to keep forms short and to the point. People are fairly protective about their privacy. Try to place yourself in your visitors' shoes. For example, if I were signing up for a simple newsletter and the form was asking for my street address, phone number, etc., I would ask myself, "Why do they need this information and what does this have to do with the newsletter?" It doesn't take an Internet savvy purpose to see that asking for this type of unnecessary information is a transparent attempt to harvest personal information. I suspect these types of questions will adversely and significantly affect the response rate. In my view, 2 pages is 'way' too long.
Concur . . . You hit the usability right on the nose, respree. For "internet forms" this advice is very true. Keep it to one page, and preferrably less than 10 items is ideal. However, if you are building forms for an internal business process, I would consider multi-page forms. They are often "told" by the process/boss/etc that certain forms need to be filled out as part of a process. Terseness is great, where you can, but often your requirements will be automating a paper form. Ideally, it would avoid any duplication of data entry and not need scrolling to fill it out. In these cases, it is often necessary to mimic the structure of the paper form - at least in segments to get user buy-in; the whole famialarity concept.