what does the Summary report output means

i am generating the Summary Report "General Statistics" Report,
i want to know what each output in the Report means?!!

Hits
Total Hits
Visitor Hits
Spider Hits
Average Hits per Day
Average Hits per Visitor
Cached Requests
Failed Requests
Page Views
Total Page Views
Average Page Views per Day
Average Page Views per Visitor
Visitors
Total Visitors
Average Visitors per Day
Total Unique IPs

Bandwidth
Total Bandwidth
Visitor Bandwidth
Spider Bandwidth
Average Bandwidth per Day
Average Bandwidth per Hit
Average Bandwidth per Visitor