Comparing EAV to Relational Table
EAV makes a lot of sense for a generic e-commerce solution. A store that sells laptops (which have a CPU speed, color, ram amount, etc) is going to have a different set of needs than a store that sells yarn (yarn has a color, but no CPU speed, etc.). Even within our hypothetical yarn store, some products will have length (balls of yarn), and others will have diameter (knitting needles).
Entity = Table / Tablename
Entity is somewhat of a “data item”. In Magento, those are for example Categories, Products and Customers.
Columns are called attributes in EAV
Attribute = Field / Fieldname
Attribute is again a “data item”, but to differ it from the Entity, in Magento, attributes are for example: Title, Description, Price, etc. for each Product entity
Value = Field Value
And Value for simplicity of explanation represents “real value” that is attached to Entity’s Attribute