find and replace with sed

Replacing characters in a text file

$ cat sample.txt
John,28,Engineer,Manager, Anna,23,Analyst,Associate, Jenna,29,Data Science,Manager, Tom,20,Engineer,Intern

Replacing delimiter in a text file

$ sed 's/,/|/g' sample.txt
John|28|Engineer|Manager| Anna|23|Analyst|Associate| Jenna|29|Data Science|Manager| Tom|20|Engineer|Intern