# RUM Glossary

## E​

### Error​

An event that deviates from the normal flow of the application which results in an issue.

### Error Rate​

Number of errors that occur per minute.

### Event​

A single unit of information, containing a timestamp plus additional data.

## F​

### Flame Graph​

A diagram that depicts the stepwise breakup of the event and time spent in each of those events

## R​

### Response Time​

The duration of time spent by the system between the start and end of an event.

## S​

### Slow Page​

Any Page which has relatively higher Response time.

### Span​

Information about the execution of a specific code path. Spans measure from the start to the end of an activity and can have a parent/child relationship with other spans.

## T​

### Target Response Time​

The ideal Response time within which the response is expected from a system

### Trace​

Defines the amount of time an application spends on a request. Traces are made up of a collection of transactions and spans that have a common root.

### Transaction​

A special kind of span that has additional attributes associated with it. Transactions describe an event captured by the sf-apm-rum instrumenting a service.

### Transaction Rate​

Number of transactions that occur per minute.