Counsellors use a professional but interpersonal relationship with their clients to make people understand what they are going through in times of turmoil or problem situations and how to adapt and alter their way of thinking to formulate a solution to get out of the problem situation.
The therapist normally conducts the counselling face-to-face with the client, however in this age of technology some are available by other means , like the internet, telephone, or video conferencing. Some therapists work entirely on what is going on at this moment and what will happen in future with the patient and not interested in the past, whilst others are more interested in a client's past history to try to see if any of that has manifested itself in the current problem(s).
Counsellors generally focus on specific problems or life changes such as bereavement or addictions and relationships and therapy sessions can be designed for individuals, couples, a family or a group.
Counselling is invaluable for treating any crisis situation, management of stress, grief and trauma, relationship problems and any emotional or psychological problems.
How often the counselling should take place, and how long a session should be will depend upon many factors like - severity of the problem presented, what the patient's mind set is at the moment, can the counsellor see a problem brewing, if so then more contact has to be done, etc.