In building terms a supporting wall is one which is vital to maintain the integrity of the building. In layperson's terms it means that if you knock a supporting wall out without replacing it with an alternative means of support the building, or part of it, is at risk of falling down or being seriously damaged. Supporting walls are not always easy to recognise. In a building with more than one floor any brick walls at first floor level will usually require a supporting wall beneath to hold their weight. This is why knocking walls out on the ground floor often requires that the upper space is supported by the insertion of new, usually steel, beams in or below the ground floor ceiling to support the floor above. Even timber stud partition walls can be loadbearing. They might be there to support the end of a run of joists or to prevent longer joists from sagging as they span a wide space. Supporting stud partition walls will be more solidly built than other partitions and will usually be supported below ground floor level by a brick or block built dwarf wall. If you are uncertain always take advice from a structural engineer and remember that building control permission is required for any major demolition/building works.