CSS selectors are indicating an element within the HTML structure of a page. Consider it as a tree with many branches, and the CSS selector is the guide to get you to the right leaf.
:eq() is letting you know which element in row we are looking for (this is starting from 0). If you have a list with many “li” elements, then the first will be referred to as li:eq(0).
So the CSS selector:
html > body > div:eq(0) > ol > li > h3 > a:eq(1)
means look inside “html” that has a “body” that has the first -:eq(0)- “div” that you will find, that has an “ol” that has an “li” that has an “h3” that contains some “a” and get the second one – a:eq(1) –
Press F12 while on a browser to see the structure of the webpage and create your own CSS selectors.
The following sheet is quite helpful, if you wish to create advanced selectors using the attributes, classes (.) or Ids (#) of the elements.