when should I use <u> and when <ins>?

Question

in output both are same, just underline the txt....

Answer 1

In practice, the effect is mostly the same, except that ins tags are ignored by some old browsers. Some exotic browser could use different rendering. I have not seen any evidence of any browser, search engine, or any other relevant software make any distinction between the two; their “semantic difference” has no practical impact.

However, I would not use ins for anything except inserted text in some sense, just because some future browsers might treat it in some way that makes sense for inserted text but not otherwise. And there would be no tangible benefit from using ins just for underlining: u is shorter markup and more widely supported. Then again, situations where you should underline text, except links, on web pages are rare.

Why not use it on your CSS style? :)

text-decoration: underline;

Answer 2

#Scotti wht do you mean by rendering
Can you clearly meaningful it?

Answer 3

underline

Answer 4

when you go stop doing this