Snowball: metrics that are "data source - and system-agnostic," meaning that a particular database is not needed to calculate the metric. Snowball metrics are designated by a small snowflake symbol: 
Examples include H-Index & document count. Learn more about Snowball Metrics
Proprietary: metrics that require a particular database or system to calculate the metric. Examples include Impact Factor & Citescore.
Journal level: metrics that measure the impact of a given journal. Examples include Impact Factor & Scopus Metrics. Learn more about journal level metrics
Document level: metrics that measure the impact of published research. Examples include field-weighted citation impact & percentile benchmark. Learn more about document level metrics.
Author level: metrics that measure the research impact of individual authors. Examples include H-Index & document count.
Altmetrics: metrics that measure and monitor the reach and impact of scholarship through online interactions. Examples include: media mentions & scholarly commentary online.
