In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

The atoms in molecules , crystals , metals and diatomic gases — indeed most of the physical environment around us — are held together by chemical bonds , which dictate the structure and the bulk properties of matter .
The atoms in molecules , crystals , metals and diatomic gases are held together by chemical bonds .

The guinea pig or domestic guinea pig ( " Cavia porcellus " ) , also known as cavy or domestic cavy , is a species of rodent belonging to the family Caviidae and the genus " Cavia " .
Guinea pigs are " Cavia porcellus " , a kind of rodent .

The United States Department of Defense ( DoD , USDOD , or DOD ) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national security and the United States Armed Forces .

The United States Department of Defense , also known as the DoD , is a department in the United States government that is in charge of the military of the United States .