You've all undoubtedly heard about the deal between Sony and Marvel regarding Spider-man's rights. If you haven't, here's the gist of it: Marvel and Sony agreed and officially announced that Marvel will be using Spider-Man in a (currently unknown) film. They're also working to bring characters from the MCU into The Amazing Spider-man. Though "Sony Pictures will continue to finance, distribute, own and have final creative control of the Spider-Man films." This is a huge step for the MCU, now having access to one of the most popular characters.
Marvel has been trying to make a deal with Sony for sometime now, so this is excellent news all around. Marvel was, as most of you know, trying to get the rights to use him in the upcoming Captain America: Civil War movie, because Spider-Man plays a huge role in the Civil War comics. But, because the Movie is coming out in a little over a year, there is a big chance he's not going to make an appearance there. The script is already finished and filming will begin in April. He could make a cameo by merely being talked about, which is more likely, or he could even be in the end-credits scene. Some have speculated we'll see him as soon as Avengers: Age of Ultron, which is very unlikely but still possible if the MCU has a few tricks up their sleeve. There's also a chance that Marvel had him already written into the script for Civil War, or are hard at work as we speak writing him in for filming.
The obvious question then, is which Marvel movie(s) will he be in? Well, Wall Street Journal has cited from an anonymous source "with knowledge of the matter" that he'll make his debut in Civil War. I still have my doubts about this. While it would be awesome to see Spider-Man in the MCU as soon as next year, it seems very unlikely. Because, as I said, the script is already finished and filming starts in 2 months. There is, like I said, a chance that Marvel already wrote him into the script or are currently revising the script. I doubt they would've already had him in the script before the deal was confirmed, because that's a huge risk taker on their part. If they hadn't been able to reach an agreement with Sony they would have to rewrite a large majority of the script, and possibly push-back the announced release date.
I do think that he will play a part in Civil War, even if just by being mentioned, but if he will make an appearance in the movie is something we won't know until the movie itself releases (or possibly the trailer.)
What I think is more likely, and what I'm most hoping for, is that we'll see Spidey in Avengers: Infinity War. Don't get me wrong, I would be thrilled with seeing an appearance sooner. I just think if he's included in Civil War as an essential character, it'll feel rushed. I have total faith that Marvel will do great wherever they put him, but I've always been a huge fan of Spider-Man and I want them to do the best job they possibly can with him. If he's in Civil War, unless he was already written into the script, I think the writers will have to rush in to change the story to Introduce Spidey and include him in the story too and it won't feel like he was meant to be there. Whereas if we don't see him until Infinity War they'll be able to write him in at the same pace as everything else and it will feel more like he's meant to be there. But I digress, I would be thrilled to see him in Civil War and I'd be happy either way, and the main reason Marvel pursued Spider-Man for so long was for Civil War because he's such a key element in the plot. But from the sound of things, I believe they're going to try to include him in Civil War, even if just mentioning him.