### aggregation:

Cluster
* Most clusters tend to be part of a larger grouping called a supercluster.
* Some clusters appear to be grouped into superclusters
  - decay into hadrons
  - have only a handful of galaxies and are called poor clusters
* are a grouping of adjacent pixel defects
  - unit of planning
* are also a crucial step in determining the distance scale of the universe
  - important socially, because they are places of co-operation and networking
  - an optional method of storing data in groups of tables that have columns in common
* are big groups of galaxies, all held huddled together by gravity
  - huddled and held together by gravity
  - crystals grouped on a common matrix
  - druzy crusts that line the fissures formed in ancient metamorphic rocks
  - geographic concentrations of competing and cooperating companies
  - groupings of related documents
* are groups of items that are closer to each other than to other items
  - machines joined through some type of high-speed network like connection
  - occupations that have similar ORPs
  - related objects accessed together
  - schools working together on similar elements of school reform
  - important to a region's economic growth
  - large groups of galaxies held together by gravity
  - local networks of firms in related industries
  - massive, and depending on their shape, can focus background light in a variety of ways
  - multiple computers connected by a high-speed, local area network
  - prominent in the large-scale distribution of galaxies in the universe
  - regions in which a sudden and astoundingly high number of e.g. leukaemia occurs
  - research teams that join forces to do specific comparisons
  - spacecrafts
  - the media through which the explorations take place
* emit X-rays from hot, ionized gas between their galaxies.
* flies prefer earthworms instead.
* form stars of all masses.
* generally form by the gravitational merger of smaller clusters and groups.
* headaches frequently surface during the morning or late at night.
  - an aggregated material which consists of a few to thousand atoms
  - one of the least common types of headache, and the cause is unknown
* micro laboratory of surface science and an example of small body systems.
* often serve as the heart of an organization's computing environment.
* play an important role linking atoms or clusters with bulk.
* show varied behaviour in their spatial distribution of heavy elements.
* stems can blight and become brittle if infections are high.
* vary greatly in density, number and types of stars as well as age.

### aggregation | cluster:

Atomic cluster
* are the ultimate nanoscale materials.
* constitute a form of matter intermediate between molecules and bulk solids.
* containing tens of atoms lie at the small end of the size scale.

### aggregation | cluster:

Cluster of galaxies
* Clusters of galaxies are the largest gravitationally bound objects in the universe
  - gravitationally-bound objects in the universe
  - themselves clustered
  - very massive objects
  - consist of hundreds to thousands of galaxies bound together by gravity
  - contain dilute and hot, X-ray emitting gas in the space between the galaxies
  - range in size from a few dozen members to several thousand
  - show more mass than is seen in stars
  - tend to form superclusters
* Many clusters of galaxies contain radio sources, and many radio sources are in galaxy clusters.

Crystal cluster
* appear as tiny orange or red dots on the white agate rind.
* are also helpful to organize scattered thoughts and to deflect negative energies.

Galactic cluster
* Many Galactic clusters display a variety of binary systems, especially near the cluster center.
* Most galactic clusters are only a few hundred million years old or less and have formed recently.