Tables
Standard tables (Account, Contact, Lead) come with Dynamics. Custom tables hold your own entities. Activity tables (Task, Phone Call, Email) integrate with timeline.
Columns
Text, Number, DateTime, Choice, Lookup, File. Choice columns (single/multi) replace picklists. File columns store binary attachments alongside records.
Relationships
1:N (one Account, many Contacts), N:1 (lookup from Contact to Account), N:N (many-to-many, intersect table). Cascade behaviors (delete, reassign, share) are configurable per relationship.
Business Rules
Declarative if-this-then-that on forms. Faster than JavaScript, runs server + client. Use for simple field-level logic; escalate to Power Fx or plug-ins for complex rules.
Modeling Advice
Model your business, not the vendor. Extend Account, Contact, Lead if your business objects map to them. Build custom tables when standard ones don’t fit.