It's pointless to duplicate the functionality of the browser's Back button. But a button like "Return to Search Results" should not duplicate the functionality of the Back button and is very useful.

For example, the Jira issue tracking application shows a "Return to search" link on search result detail pages. The link persists even if you drill down and edit a search result, and it always returns to the search results page, no matter how many pages you've clicked through into the search result. This is very useful.

I think it depends on several factors.

Firstly - who are the target users? Are they expert/intermediate users? This may reveal some behavioural insights to the use of the back button. Sometimes it's better to re-label a link to point them to where they most likely want to go to, as opposed to placing links that "always go back the previous page" everywhere.

Also - there can be a confusion between "back" and "take me home", and it depends on the context of the navigation - where the users are in the site, and more importantly, in their task. Thus, the user may decide to use the back button over a link (or vice versa). I think this will require user testing to tease out the details.

In terms of search, I think it will be useful to have a link that takes a user back to their search results. Whether this feat is technically difficult or not depends on how your system is set up, and your developers/managers may or may not be willing to change large parts of the code for this. However, if you can get user feedback about the use of a "back to search results" link, they may realize it's more important than they thought and work to improve the system that way.

I do feel that we ought not to take navigation for granted - particularly when users are usually alone when they interact with a site, with no human feedback or guidance whatsoever.

HTH

I would only add that a link clearly saying "Back to search results" gives user confidence and feeling he's in control of his actions. It's about user control and freedom.

As Boon mentioned context is important. To give an example - with tabs being present in all major browsers, many people tend to open pages (search results pages in this case) in new tabs. Back button will not work for them in such case should they decide to see search results in newly opened tab.

I personally wouldn't rely on the browser navigation only, as the result of using Back button may sometimes be ambiguous.

I firmly believe that there is absolutely no reason to duplicate the functionality that all standard browsers provide, including the back button. People understand quite clearly what the button does and how it works. As long as your search results come back up after using the back button (meaning you don't get one of those "would you like to resubmit the form" messages), then there is no reason to have a Back to Search Results link. I also disagree with pkreglicki - I don't see how the result of using the back button could be ambiguous. It serves a very clear and distinct purpose.

If you are looking for research to back this up, the easiest way is to use analytics. Set it up so the search results records differently when someone clicks on the search button vs. when the page is viewed a second time via the back button. Then review to see if your users are going back or performing the search a second time in cases where you have users viewing the same search results multiple times. In my past experience with tests like this, the users almost universally used the back button on the browser, so to me it was pretty clear that they knew how it works.

Another thing to think about is how links like "Back to search results" could potentially harm the users' experience on your site. If you explicitly duplicate browser functionality like this (or with Print links or Back to Top links), then you may make more novice users think that they can't use their standard methods for performing these actions. A user might think "Why is this link here? Can't I just use the back button like I do on other sites?" Since your goal is likely to support novice users with a link like this, you may be doing more harm than good overall.

A final thing to think about is server performance. Depending on how your search and how your site are set up, using a link like that could cause a performance hit on your server. If you have browser-level caching enabled, then a simple use of the back button will not reload the page, which means the server will not be hit again. But if you have a link to the search results again, it will invariably request the data from the server again, increasing your load.

Consider how pages work when viewed away from their original context ie. outside of the browser's history.

For example, when users share links, the sender might relate to the page in terms of how it fits within a series of steps that they themselves have taken, whereas the recipient, upon seeing the page for the first time, may benefit from understanding how the page fits onto the site as a whole.

Similar issues come into play when you consider users bookmarking pages for later viewing.

In addition to links on pages and browser navigation (which I think both are useful and indispensable) I would like to add just one relevant idea. Make your URLs also help user with the navigation. I mean if the URL is like this:

http://uxexchange.com/questions/1540/

it's short, understandable and every user may travel through the site by deleting some parts of the URL back to the nearest slash. Deleting "1540" will take you to the questions directory and so on. Compare it to this imaginary example:

http://uxexchange.com/?q=%E8%E4%E8%EE%F2%F1%EA%E8%E9+%E7%E0%EF+&num=10

I can confidently say (having carried out numerous observed tests) that a sure fire way to annoy a user would be to mess with the functionality of a browsers back button, or to use a technology which prevents the back button from behaving as the user expects.

If you are duplicating a browsers functionality purely because the technology used breaks the browser functionality then you should consider a new technology solution.

I have never come across a user who doesn't understand the back button either.