Information architecture is organizing, grouping and classifying content so that users may find what they need quickly, go from one block of content to another without doubt and end the process efficiently. A house can be built without architecture; a website, app, or system can too, but, in both cases, the results may be disastrous.
Prototyping is one of the phases of Design Thinking that aims at making all ideas tangible. That is, materializing them. Prototypes are created in the starting phases of a project and they generate savings as they make it possible perform route corrections before heading on to development.
Prototypes are designed following good practices in UX and design, but they still need user testing. Prototype tests are quick and identify problems in the beginning of the project, when the cost of making changes is lower.
Card sorting is a methodology that helps discover how your client thinks, acts and speaks. This technique, for example, allows the building of clearer menus, with names that make sense to the user, avoiding their getting lost and abandoning the purchase or any other activity that they may need to perform.