Entity Framework

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

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