I am creating a HTML form. I am confused to have all thing on 1 long page or to have various pages. Which is better for me? When should form be split to various pages? 
I think it’s safer to have it all on one page, personally, because breaking it up can have consequences for when you want to go back a step. But it’s up to you. At least when it’s all on one page you kind of know where you are in the process. I dread going from page to page to complete a form.
[font=verdana]As Ralph says, the more times people have to go from one page to another, the more likely you/they are to encounter problems. Every time they have to load a new page, you run the risk of the connection failing, people timing out if they take longer than expected on one page (eg if they are interrupted in the middle of filling it out), and if they want to go back and change something on a previous page you have the dilemma of whether to use the browser’s “back” button or a link on the page, and whether it will store other changes made since then. There’s also a bigger risk that they will get part way through, get bored and give up, especially if you don’t make the process obvious, clearly showing how far they’ve got still to go, and when they have completed it.
The one advantage that multi-page forms can have is partial saving can mean less likelihood of people losing lots of data. If the website saves people’s data as they move from one page to the next, such that if they drop the connection or get called away it is still there and they can continue where they left off, that is a plus point, because it means that the most that will ever be lost is one section rather than the whole lot. But that is more complex to set up and has greater security implications.
Off Topic:
I see you’ve asked this question elsewhere … why did we get “discombobulating”? 
Thanks. 