You click a reference and another document appears. Then compare what you see on the screen with the actual content of my home page shown below. The text is enhanced by coded instruction delimited by angular brackets called tags. The author must be familiar with the role played by these short instructions. A recent book about Internet is likely to contain a chapter explaining html tags.
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Ludwik's Homepage Ludwik Kowalski. Welcome to my home page. Choose one item by clicking on its link below. How I webcast a topic. One file of the folder of a topic is simply a list of subtopics.