Block elements create key structural parts of web pages. Block elements will seperate themselves from surrounding content with a line space above and below. They will also take up the full width of the parent space.
Block elements are different from inline/phrase elements. You'll notice that some common block elements include...
Inline elements are generally (but not always) associated with chuncks of text and are there to markup chunks of text. The text is within the line, or in line. If you want to bold some text, then using the <strong>...<</strong> tags would do it. STRONG is an example of a popular inline element.
Other inline elements include...
There are lots of great resources on the Web. However, W3Schools has references both HTML Tags and CSS Properties. Both of these should be bookmarked and referenced weekly for ideas and learning syntax.
Another great resourcs is the Mozilla Developer Network.