After reading the specification and claims, the examiner searches the prior art. The subject of searching is more fully treated in MPEP Chapter 900. See especially MPEP §§ 904 through 904.03. The invention should be thoroughly understood before a search is undertaken. However, informal cases, or those which can only be imperfectly understood when they come up for action in their regular turn are also given a search, in order to avoid piecemeal prosecution.
PREVIOUS EXAMINER’S SEARCH
When an examiner is assigned to act on an application which has received one or more actions by some other examiner, full faith and credit should be given to the search and action of the previous examiner unless there is a clear error in the previous action or knowledge of other prior art. In general the second examiner should not take an entirely new approach to the application or attempt to reorient the point of view of the previous examiner, or make a new search in the mere hope of finding something. See MPEP § 719.05.