See the Garbage Collection Handbook

Garbage collection is one of the features you may use to distinguish a "high-level" language from a lowlevel language

High-level languages "hide irrelevant details" (behind abstraction).

Glossary

• Reachability ::

  Can the runtime reach this data?

• Conservative GC
• Garbage ::

  Unreachable memory

• Managed language ::

  A language which automatically manages memory

  Contrast with a language like C

• Precise GC
• Mark-and-Sweep ::

  two-phase traversal of all reachable memory in a program

  In the first phase, any data which is reachable is marked

  In the second phase, any data which is not marked is swept (i.e. freed)

• Weak Reference ::

  A reference which does not protect an object from garbage-collection