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.
Alpha Chi Sigma (Î±ÏÏ) is a professional fraternity specializing in the field of chemistry. It has both collegiate and professional chapters throughout the United States consisting of both men and women and numbering more than 69,000 members.