This is a special style of writing that's often used in newspapers and journal articles. Because newspapers used to have limited space (when they were all printed on paper), it was common to leave out some words in order to fit articles onto a page. Newspaper writers often leave out the word "the" when the meaning is clear without it.
You may notice that newspaper titles will leave out even more words. For example, you may see a newspaper title like "Man Shoots Own Son." This would be terrible English if you said it in a conversation, but it's normal for a newspaper article title.
Newspapers also omit commas in some cases where they should normally be used, and newspapers put only one space between sentences (in other formal writing, the standard is to put two spaces between sentences).
If you are writing in any format that is not a news article,* you should use the word "the" in the places where you've included it.
*(Edited to add: Irene is also right that this same style is used in ads, reviews, and short blurbs, in addition to news articles. The reason is the same -- the writers want to make the text shorter.)