The contribution presents an overview and analysis of research results concerning the influence of Internet on mathematics
teaching and learning. The studies have been divided into categories according to their research focus. The second part focuses
on free web resources. Website functions are being discussed in comparison to textbooks from the learning process point of view.
Based on the investigation of a range of websites, the benefits and risks associated with web sites use in mathematics instruction
are stated. These include an analysis of some mathematical and didactical errors in these resources.