Information structure in Dutch — what is already known (the topic) versus what is new (the comment or focus) — is expressed partly through word order. The topic, or given information, tends to appear early in the sentence while new information appears later. This is why speakers shift elements to the front of a clause: to signal that the element is being set as the topic of discussion. Dat boek heb ik al gelezen places the book as topic, with the reading as the new comment.
Focus — the part of the sentence carrying the main communicative stress — tends to fall at the end of the Dutch sentence in neutral utterances but can be shifted leftward by fronting. Cleft constructions allow even stronger focus: Het was Maria die belde (It was Maria who called). Contrastive stress can also shift focus without changing word order, simply through speaking emphasis placed on a particular word.
Discourse particles such as dan, toch, wel, even, maar and hoor calibrate the relationship between what is said and what is assumed. Dan signals an inference or result. Toch contradicts an expectation. Wel counters a negative assumption: Ik heb het wel gedaan. These particles are invisible in grammar textbooks but pervasive in real Dutch conversation — extensive exposure to native speech is the main way to acquire them naturally.