Best software to use when surfing the internet.

Last night I did a search on the internet for a tree that's in our yard that someone had given me the name for & I was wanting to find out info about it & when I clicked on one of the links that came up from the search; a window popped up & said that my pc was under attack & it had captured 2 culprits. It then popped up a window asking if I wanted it to erase the captured attacks & without thinking I clicked the erase button & then a window popped up & gave me the option or 'Run' 'Save' or 'Cancel'....(it would have started a name with a .exe extention) & that set off an alarm.... besides the fast beating heart..etc.

Anyway, I looked at the program that had found/captured these attacks & it wasn't a program that was on my pc, so I hit the red X to close that window.... didn't want to hit the other 3, because that might have started the attack for sure. Then I closed the window that was open; that I had clicked on to look at the tree info. Won't look for that tree info anymore.

Just want you to be cautious if you happen to click on a website & it says your computer is under attack.

What is the best software to have on my pc in the event that I or my DH or DGKs would activate an attack from a website?

TIA,
Jan in Central Illinois