All systems have architecture. THe question is if the architecture enables the system to exhibit the qualities needed to be successful in its environment.
If you are creating class or database models, you probably don't have a complete list of data types; "string" for example. This is how to add data types to your model in Sparx Enterprise Architect.
Project managers often contact the enterprise architecture team and ask, "Do I need an architect for my project?" The answer is simple. Every project has an architect, whether or not they are titled as such. The real question is how much time should your project dedicate to architectural decisions.
Unified Modeling Language (UML) is very much just that, a language. UML is a visual language for representing complex concepts. It removes ambiguity from technical illustrations and provides clear representations of design elements. If you want to greatly improve your technical communication skills, start using UML in your diagrams.