“Snippets” are blocks of content that Google finds so relevant for a given search that they highlight it in the search results.
An example is this search
(in Dutch) where a page of my website is highlighted because it provides the exact answer.
So, snippets are huge traffic drivers and you might want to have them.
Lately, Google is also pushing content from PDF’s in snippets
. This is interesting, because this means there is no need to change PDF’s to “real” page content anymore and this is an extra opportunity to get highlighted in snippets.