From another question:
Full table scans, index range scans, fast full index scans, nested loops, merge join, hash joins etc. are merely access systems that must definitely be understood through the analyst
Can someone explain each one of these as well as provide where I'm able to perform some further reading through in it?
For additional around the joins, I would suggest reading through some articles from Jonathan Lewis:
For more information on reading through Execution Plans and interpretation the things they mean I would suggest it:
Section 11.3 Summary of Joins