If the Organization Wide Settings (OWD) in your Salesforce Org is set to anything other than “Public Read/Write” for any of the standard or custom objects then it is more than likely that you will need to setup some sharing rules to share these records with other users. So what are the different ways to share records? Here is a checklist of all the different ways (19 that I could think of) in which you can share records in Salesforce. You can use this as a quick reference guide to help you determine which of these options will be most appropriate to meet your business requirements.
And the following presentation gives you a little more information about each of these sharing options.
- How Salesforce Determines Record Access for a User
- Record Level Access: Under the Hood
- Designing Record Access for Enterprise Scale
Have I missed anything? Please comment below and I will add that to this list.