Sentence:  <WSD>Abjad</WSD> is the writing system used in this book, and it's also the writing system used throughout the Arabic world. For instance, most newspapers you pick up in the Middle East use the <WSD>abjad</WSD> writing system, whereby the consonants are included but not the vowels. 
Meaning of the word marked with <WSD> tags:  A writing system for Arabic, historically also employed as a numeral system, in which there is one glyph (symbol or letter) for each consonant but vowels are not specified.