Concept maps are a phenomenal tool when it comes to explaining complex theories and proposals that are made up of a number of main ideas that relate to others. There are tons of apps out there designed to help you develop concept maps such as DIA (GNU) or InfoRapid KnowledgeMap (Shareware) but not all of them are as practical and fully featured as CmapTools.
What makes CmapTools stand out from the rest is its ability to create online concept maps that include attached files and links to other sites. This allows for interactive diagrams made by this tool that allows you to interact with content through your browser. Also, sharing your concept maps and its resources online is a very useful feature. There are tons of available public servers that will store your maps and all of the attached files associated with it.
Making a concept map is simple, just insert diagrams by double clicking on your screen background and drag arrows wherever you want. Users can then modify shapes, colors, fonts, link shapes, or add a background image and attach resources to each shape.