IFrames are not supported with XHTML 1.0 Strict Doctype.
When you use IFrame and your doctype is XHTML 1.0 Strict, then you cannot pass the W3C Markup Validation test. You always get errors.
The errors are like:-

Problem:
I want to create a dynamic HTML table with a row starting after certain number of columns, i.e. like, i want to create an html table which automatically generate new row after 3 columns in a row.
Solution:

Meta tags are HTML tags which provide information that describes the content of the webpage a user will be viewing.
Meta tags have two possible attributes: