Scopes and Slugs

I am still working on the sort issue but I ran into the words scope and slug and I am trying to get a grip on what they are doing.

app/controllers/application_controller.rb

 def slug
    Apartment::Database.current
  end

  def crowdslug
    @_crowdshop.slug
  end
  helper_method :crowdslug

  def slugged?
    slug != "public"
  end

  def find_company
    @_company = Company.where(slug: slug).first
  end

db/schema.rb line: 115

  create_table "companies", force: true do |t|
    t.string   "slug"
    t.string   "name"
    t.integer  "account_id"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.boolean  "enabled",    default: false
    t.string   "password",   default: "",    null: false
  end

  add_index "companies", ["account_id"], name: "index_companies_on_account_id", using: :btree
  add_index "companies", ["name"], name: "index_companies_on_name", using: :btree
  add_index "companies", ["slug"], name: "index_companies_on_slug", unique: true, using: :btree

config/initializers/apartment.rb

Apartment.configure do |config|
  config.excluded_models = [
    "Company",
    "Account",
    "Product",
    "Variation",
    "Tax",
    "CrowdshopsProduct",
    "PaperTrail::Version"
  ]

  config.use_schemas = true

  # config.default_schema = "excluded"

  # configure persistent schemas (E.g. hstore )
  # config.persistent_schemas = [ "public" ]

  # supply list of database names for migrations to run on
  config.tenant_names = -> { Company.pluck(:slug) }
end