Anadiplosis repeats the last word of one phrase, clause, or sentence at or very near the beginning of the next. it can be generated in series for the sake of beauty or to give a sense of logical progression:

• Pleasure might cause her read, reading might make her know,/ Knowledge might pity win, and pity grace obtain . . . . --Philip Sidney

Most commonly, though, anadiplosis is used for emphasis of the repeated word or idea, since repetition has a reinforcing effect:

• They have forsaken me, the fountain of living waters, and hewed them out cisterns, broken cisterns that can hold no water. --Jer. 2:13
• The question next arises, How much confidence can we put in the people, when the people have elected Joe Doax?
• This treatment plant has a record of uncommon reliability, a reliability envied by every other water treatment facility on the coast.
• In the beginning was the Word, and the Word was with God, and the Word was God. --John 1:1

Notice how the main point of the sentence becomes immediately clear by repeating the same word twice in close succession. There can be no doubt about the focus of your thought when you use anadiplosis.