Aside from company sponsored 401(k) plans, investors can use either traditional or Roth IRAs to invest for retirement.investors. In a more recent development, companies have also begun offering the choice between traditional or Roth 401(k)s. So, it is important to understand the relative advantages of each type of account. See a good summary article here, WSJ.
Dolvin, Steven D., "Traditional vs. Roth IRA" (2014). All Chapters. 122.