- EF v1 was released in 2008, and everybody hated it
- EF v4 (there was no v2 or v3) was released in 2010 (now old, deprecated). See EF data/model first, the original EF 4 database/model first approach, with edmx designer and "Entity SQL"
- EF v4.1 was released in 2011 and included Code First.
EF v6 was released in 2013.
- EF Core v1 (originally "EF v7") was released in 2016 (NB: EF v6 was still supported and recommended for most scenarios)
- NHibernate is the other big ORM. It's more mature than EF Code First, but the legacy is confusing (multiple ways of mapping, old HQL/Criteria style queries)
- Dapper is a minimal ADO wrapper ("micro-ORM" without the R). For optimized SQL, but you can do native SQL anyway within EF and NHibernate.
- There are intermediates between heavy ORMs like EF/NHib and raw ADO/Dapper, like PetaPoco and SimpleData. There are also older mappers like Castle ActiveRecord.
- IMHO for most purposes, EF Code First is the easiest to get up and running, and then refine and upgrade
- NHibernate is still better for more complex requirements and scaling
- For optimized low-level stuff, just use Dapper/ADO