Iframe Tag just adds another window on your Webpage and due to which whenever a browser loads a page with an iframe it loads the original Page and Iframe as a separate 2 different pages. So in some cases Iframe is not-supported and thus, displays an Error.
Sigma is a Greek letter that corresponds somewhat to our letter S and thus sigma is often used to stand for some concept that starts with S. There is an upper case (capital) sigma and a lower case (small) sigma. They are and. is most ofter used to indicate a sum.
Sigmoid, curved in two directions, like the letter S, or the Greek sigma. The Elements of Botany Asa Gray. sigma, sigâ²ma, n. the Greek letter corresponding to our sâwritten Ï (capital), Ï (small initial) or Ï (small final). Chambers's Twentieth Century Dictionary (part 4 of 4: S-Z and supplements) Various.