What exactly is varicose veins?

What exactly is varicose veins?

Having varicose veins isn't a major problem, right?

It's just not visually appealing... Is there any procedure or surgery that can remove it?

After gaining weight rapidly~

It looks like a purple line on the back of my left calf, but it doesn't interfere with daily life, so I haven't gone to the hospital. It's not swollen or anything, and I don't feel any discomfort, so I probably don't need to visit the hospital separately, right!?