So, there's this spider on my windowsill, and my friend is really into spiders and knows a lot about them, but when he saw this one, he couldn't identify it. We've been trying to figure it out for a while! It's about an inch or maybe an inch and a half in length. What kind of spider is this??
The spider in your photo is a grass spider, in the genus Agelenopsis, and in the spider family Agelenidae (funnel weaver spiders). Based upon its size, I suspect this it is Agelenopsis pennsylvanica, but I can't be sure of that from just the photo. These spiders normally live outdoors in yards, gardens, fields, and forests. I can't tell from your photo whether this one is inside or outside the window, but they occasionally will make a web indoors if insect prey is available. They make flat webs with a funnel-shaped retreat at one end in which the spider hides. These spiders are very fast runners, are not aggressive, and flee when disturbed. They are generally considered to be harmless to humans. Bites are very rare and usually much less severe than a bee sting. I have included some links below to webpages with more information about this type of spider.