Many researchers say that UFO observations can be classified according to their features. These categories include:

Saucer, Toy Top or the disk shaped aircraft without any visible or even audible propulsion systems.

Large Triangular aircrafts with triangular light patterns.

Cigar Shaped aircrafts with lighted “windows” though there are some meteor fireballs which are sometimes reported looking the same way, these fireballs are completely different phenomena altogether.

There is also a system of description called the Hynek system which was developed by Dr. J. Allen Hynek. This system divides the sightings into six different categories. It separates sightings based on their proximity, using 500 feet as a cut off point. Then it subdivides the divisions based on the viewing conditions and/or special features. The distant sighting categories include:

• Nocturnal Lights- Unexplained lights seen in the night sky.
• Daylight Discs- UFO seen in daytime.
• Radar/Visual Cases- These are the UFO’s seen both by the eye and on the radar at the same time.

There is also a close encounter subcategories which are considered to be of more value as evidence as it has some physical effects that can be measured and because it is not seen at a distance, they are less likely to be the cause of a misperception. The categories include:

• CE1: These include the strange objects seen at a close range but without it having any physical interaction with its surroundings.
• CE2: Is also a CE1 case but this time, it created a physical evidence or it has cause an electromagnetic interference.
• CE3: Is a CE1 or CE2 case but this time the entities within the UFO are seen.

There are many other categories formulated by various UFO research groups but the ones above are the ones most commonly used.