Focus Your Attention
A mantra -- a word, a word-phrase, or a sound -- may be used to focus attention. For most meditators, during the early stages of practice before meditation flows spontaneously, listening to a mantra is more helpful than "waiting and observing" because it supports concentration.
Roy Eugene Davis
Mantra technique begins with intentional silent vocalization of the mantra, for example "hong-saw":"hong on the in-breath and "saw" on the out-breath.
After this has gone on for a while, we can notice that the mantra will continue to be chanted in our mind without conscious effort. As this continues, we can be watchful for the transition from concentration into the state of meditation itself, when boundaries drop away and we simply fall into a state of blissful peace. At this point, technique is no longer necessary. If we drop back out of meditation, we can always pick up the technique again.