Term Kind Topic What it is
Tail-Based Sampling Post-Trace Sampling, Intelligent Sampling practice Sampling Deciding whether to keep a trace after it completes, so that errors and slow requests are always retained while ordinary traffic is sampled cheaply.
Trace Sampling Strategy Head Sampling, Tail Sampling practice Sampling Deciding which traces to keep, since retaining all of them at scale is unaffordable and retaining a random few loses exactly the interesting ones.