An intelligence officer is a person employed by an organization to collect, compile and/or analyze information (known as intelligence) which is of use to that organization. The terminology of 'Officer' is a working title, it is not to be confused with rank as in the military or police where sergeants are also 'Police Officers' and enlisted ranks can be Intelligence Officers. Organizations which employ intelligence officers include armed forces, police, civilian intelligence agencies, customs agencies and private corporations.
Based on scientific and technical characteristics of weapons systems, technological devices and other entities.
Please note, the difference between MASINT & TECHINT is that TECHINT involves analysis of weapons systems in the custody of the organization which commissions such tests, while MASINT involves analysis, or remote sensing, of trace evidence left behind by the weapons systems ( unintended emissive byproducts, or "trails"—the spectral, chemical or RF emissions an object leaves behind which serve as distinctive signatures).
An officer that analyzes collected information and results of operations to determine the identities, intentions, capabilities and activities of hostile individuals or groups and to determine requirements for future operations. After analysis, analysts are also responsible for the production and dissemination of their final product.
An officer that works to prevent detection, penetration, manipulation and compromise of the intelligence agency and its operations by foreign or hostile agents.
Intelligence Agents are individuals that work for or have been recruited by an Intelligence Officer, but who are not employed by the Intelligence Agency of the Intelligence Officer. Sometime around 2000, the United States Intelligence Community adopted a more "corporate" vocabulary and began referring to agents as assets. Intelligence Agents can be of several types:
A primary source of intelligence information. This is the classic HUMINT source.
An agent that identifies and approaches potential sources (eventual source agents) for assessment or recruitment. In Counter-Proliferation (CP) access agents are often scientists. In Counter-Terrorism (CT) access agents are often religious or ideological leaders.
An agent or intelligence officer who accepts direction from two or more intelligence agencies. Known as triple agents when the number of directing agencies is three.
Contrary to popular belief or what is seen in Hollywood films, professionally trained intelligence officers are never referred to as agents, secret agents or special agents, they are referred to as Case Officers or Operations Officers. Agents are the foreigners whom betray their own countries to pass information to the Officer; agents are also known as confidential informants (in law enforcement lingo) or assets.
^Strategic and Competitive Intelligence Professionals, Board of Directors, 
^U.S. Department of the Treasury, Office of Intelligence and Analysis Brochure, 
^Department of Homeland Security, Deployed Intelligence Officers and Protective Security Advisors, , accessed Jan 8 2013