Galactic Society Technology Levels:
Tier 0: Precursor Technology
Precursor technology represents the highest achieveable form possible in the universe (that we know of). It encompasses technologies and techniques that are only found on former precursor worlds. The Yuan (working name) are the only known tier zero society from their worlds dotted acrocc the galaxy. While some tier one species have be known to use precursor tech; because they do not have a low level understanding of their functions/processes nor he ability to create more of the technology, they are not considered to be a tier zero tech civilization.
Some examples include stellar manipulation (Dyson spheres, changing stellar makeup, collapsing stars, etc.) planetary scale construction (hollow worlds/machine worlds, planetary scale mining, planetary collapse, etc), hyper-space maniuplation, the ability to harness vacuum energy, portal technology and more. Nearly all of this level of technology is considered to be lost to the galaxy.
Tier 1: Hyper Tech/Pre-Precursor:
Civilizations in this tier are able to use exploit exotic sciences and materials. Examples of this are hyper-fine subspace/hyperspace navigation, exotic metallurgy mastery, advanced sentient machines and colossal scale construction (among the largest starships in existence, large scale planetary construction, space construction, etc) to name a few. A key factor for races to be considered tier one is the ability to either partially withstand or combat precursor technology or having the ability to interface with it. Currently there are only X tier one societies: The Kiko Mahn Stellar Hegemony, The Traders Guild and the Galactic Commerce Exchange. The Kiko are able to use precursor technology to a great extent though they are considered tier one because they cannot create new pieces of tier zero technology. The Traders Guild and the Galactic Commerce Exchange both leverage their massive populations and economic weight to consistently stay technologically ahead of the lower tier species. The are not, however, considered to be more advanced than the Kiko. 
Tier 2: Super Advanced Tech:
Super Advanced Tech is a broad category that covers most of the galactic societies. Noteworthy members include the Human-Deliah Coalition (and the associated organizations), client species of the Kiko Hegomony: the Bolar (an arachnid species of mostly scholars, scientists and engineers), the Xyx Xaax (an Apocrita like species used by the Kiko as a warrior caste) and Mi’thia Tuu’al ([working name] another species of natural engineers though more focused than the Bolar). Other noteworthy example are constituent species of the GCE and the sub-guilds that comprise The Traders Guild. 
Technological requirements generally include: an advance understanding of hyper-space physics and travel including the ability to do semi-fine hyper-space navigation, large scale vacuum construction, large scale planetary construction, hyper-scale agriculture and though not strictly necessary having a species population over 100 billion members is common. 
Tier 3: Hyperspace Capable:
Societies that are just burgeoning into the galactic space typically fall under this category. The bounds of this tier are the ability to consistently travel between a destination star and the original star. At the other end the line gets more blurred. Currently there isn’t a hard boundary separating tier three from two but there are some general similarities. Most tier three societies don’t have client species. Typically this is the the most defining characteristic. These societies also usually have smaller scale vacuum construction and don’t have the same scale planetary construction as their more advanced counterparts. 
Tier 4: Space Flight Capable:
Any society that has advanced enough to escape the bound of their home world is considered to be a tier four society. They cannot, however, be capable of consistent hyper-space travel. Some tier four societies can make use of hyper-space but typically this is random or not consistent enough to be useful.
Tier 5: Pre-Space Flight:
Any species that has advanced enough to form societies fall into this tier. All natural species of higher tiers get their start here. Tier five is bound by the ability to launch either a member of their race/society or an machine into stable orbit around their world. For every space flight or hyper-space capable society there are a dozen or more pre-space-flight societies. While never thought of by the more advanced peoples these races, societies and other organizations make up the vast majority of sentient life in the galaxy.