I saw this insect in my house in Kolkata (India) on 2 April, 2018 after a storm at around 8:00 p.m. I would like to know what insect it is. Thanks in advance.
I would concur with user22542 --> order Diptera: family Dolichopodidae
Supporting evidence outside of wikipedia is on an Australian website. http://www.bowerbird.org.au/observations/35021
I don't suggest them to be the same species, however potentially related as they seem to live in grassy places across the globe.
It is a species of fly, or of the insect order Diptera, insect family Dolichopodidae. The exact genus and species is uncertain as there are many hundreds of species. See the link below. You can also search Google images for these names where many similar fly photos can be seen.