They are educated, and experienced in the field of Arboriculture. Requirements of the knowledge of trees is extensive due to how broad and complicated the subject can become, therefore intense training is a must. Certain guidelines have been established to follow, as most other professions have. Most Arborist's have had many years of field experience before they even attempt to become certified. An exam must be written, and a high passing grade must be met before one gets the SEAL of approval. An Arborist will always be happy to show the proof that he or she is certified, and always ask to see it! This will guarantee that the work that will be performed will most likely be done by someone that cares about you, and your trees. Ongoing training is a must and a necessity, to keep up with new technology, and techniques, being introduced monthly. Re certification is done every three years.