When to use de/del

When to use de/del
 

What are the grammar rules for when it's appropriate to use de/del? :thinking:

Thank you

de = of
del = of the (singular masculine article)
de la = of the (singular feminine article)
de los = of the (plural masculine article)
de las = of the (plural feminine article)

unless the article is part of a name:

"las palabras del salvador"
"importado de El Salvador"

"Noticias del país"
"Noticias de El País"