Is there a reason why the signup page on many websites are totally separated from the rest? I noticed that it results as a single page, where there is only the logo of the site and the signup form. No footer, no links, no header etc. The page seems to be totally separated from the rest of the site. I think that it could depends on the fact that users must not go away from this page, but I'm wondering how can I go back and return to the home page?Some sites (es. Linkedin) don't allow you to go back, and you have to rely on browser back button. What do you think about it?Is it a UX guidelines or just a "trend"?
In addition to all of the previous answers, another factor for the independent sign-up page is that there may be some referral data at play. A great deal of services want to know where a user was linked from – be it Twitter, Facebook or some other site – in order to measure the impact of their advertising efforts or influence. Additionally, there may also be some sort of bonus involved for the referrer or end user. For instance, if I send someone to my webhosts' sign-up page with a specific string appended to the URL, they get a discount and I can get a sign-up bonus. Allowing the user to access the site outside of that page prevents this type of deal from working.
However, I don't think that completely disconnecting the end user from the rest of the site is that great of an idea. I would rather take the risk of not getting 100% accurate analytics data or missing out on a discount here or there than to allow for the perception of my service being untrustworthy or poorly architected.
If a user is directed to a sign up page then the only thing available for the user must be to sign up. When it comes to user experience the user must get what he/she is looking for and what he/she has come there for. Keeping other options/ information on the page may not only be less productive but may also host as a distraction for the visiting user. Hence the standalone page for it. This decision may be based on the changing rather evolving UX trends. However there may be guidelines that govern it that I am unaware of.
However there must be some kind of navigation option on the page that may help the user to exit the page without having the leave the site/ application. Unless it is the requirement of the site that the user has to be a member to view anything this kind of approach may be avoided, since if a user changes his/her mind of signin up and wants to browse through the content then it should be possible without having to exit the site and browsing back to it. Else that will be a dead end and the navigation of the site will be incomplete.
Here I'm giving a try- there are many dependencies the service provider would validate while anyone sign up for them. 1. Correct information 2. Security 3. Avoiding spam
From user experience point of view during signup, user has to depend upon his cognitive load. they have to recollect many things and also try different options. So to reduce this load, sign up page will be made as simple as possible.
Now a days, in many signup page, they are not asking to fill the form, instead user information is taken from different trusted sites which user has already a part of it. In this way, user also doesn't required to maintain different mail ids also websites too doesn't need too either.
Coming to your question about why there is no provision to go back to the main page, may be because they want to avoid spams as I mentioned above. And user to focus on this part itself.
May not be relevant but helpful insights http://janrain.com/blog/social-login-trends-across-web-q4-2013/
In addition to the reduction to cognitive load -
It might sometimes be a technical limitation. Many sites take you to completely different area as that separated area might be run by a completely third party site. Contests and Loyalty on some Publisher properties can run this way.
That may partially answer the back button dilemma.
The other half is perhaps to prevent double entry (if the user decides to refresh the page, or go back and then forward again.)
There is also the risk that if the user goes back and then forward again, they could lose the data they already typed in.