As Winston Churchill once said, “to improve is to change; to be perfect is to change often." It's a maxim Facebook seems to have adopted wholeheartedly when it comes to the News Feed.

Posts appearing in your news feed today likely look different from the posts you saw six months ago, both in appearance and content. The simple reason for this is Facebook is learning more about you, and that means the company's news feed algorithm is better at determining what you like and what you dislike.

See also: How to Curate Your Facebook News Feed

The average Facebook user has roughly 1,500 stories per day that could appear in their news feed. Facebook surfaces about 20% of those stories. That's where the algorithm comes in, and that's why Facebook is constantly tweaking it.

The social network has been particularly busy with the News Feed the past six months, releasing a number of algorithm updates and a significant redesign. It's all part of CEO Mark Zuckerberg's ultimate goal for the product: to provide every user with a perfectly personalized digital newspaper.

What exactly has changed in the News Feed algorithm in recent months, and why? Here's everything you need to know.

What You're Seeing More Of:

Auto-play Videos (Including Ads) Facebook first tested auto-play videos in the mobile News Feed in September. Facebook's web version got auto-play videos in December. The company began testing auto-play video ads a week later, but postponed full implementation. In March, Facebook announced auto-play video ads would begin to roll out to all users over the "next few months." That means some of you know the ads all too well. But if you're thinking "auto-play ads? Never seen one", then rest assured, you will. These videos play automatically as you scroll through your News Feed. They won't have any sound unless a user clicks on them. This does not include shared videos from third party sites, like YouTube, but only videos uploaded directly to Facebook. What do you think of auto-play video ads in your Facebook News Feed?

Larger Photos Facebook began to include larger images in the News Feed as part of the platform's redesign announced in March. Photos now span the entire width of the News Feed. This larger photo feature was about the only one of a set of News Feed changes promised back in March 2013 that actually arrived. We were promised tabs and multiple feeds that users could subscribe to; none have surfaced so far. The only other change from this round worth noting: the default font changed slightly. Facebook rolled out a news feed redesign last month that means pictures appear bigger in news feed. The bottom image is from the old design.

High Quality News Stories Facebook altered its news feed algorithm in December in order to surface more "high quality content" on the platform. That means more news and current events, according to the company's blog. This change affected the News Feed in both its desktop and mobile versions, although Facebook says mobile users should notice the greater difference. The company hopes to be a competitor to Twitter when it comes to breaking news and the social conversations that result from it. This is also the reason you may notice more ...

Resurfaced Content As part of the algorithm change that surfaces more "high quality" content, Facebook really wants to make sure you saw those stories — to the point where they will pop up even if you've read them. That may be annoying for some users, but the social network really wants to make sure you're not missing a conversation your friends might be having around those hot-button articles. Here's Facebook's explanation for the change, courtesy of the company blog: "After people read a story, they are unlikely to go back and find that story again to see what their friends were saying about it, and it wouldn’t bump up in News Feed. With this update, stories will occasionally resurface that have new comments from friends." Still, users complain about seeing the same content over and over. Our recommendation: Like the stuff you want to see more of, and either don't engage with or hide the posts you don't enjoy (via a drop-down menu next to the name of whomever posted it). Be aware that if you hide a post, you're less likely to see any posts from that person.

More Content from Brands Facebook made another small algorithm tweak in February to help brands expand their audience: if a brand tags another brand in a post, their content can now reach fans of both brand pages. For example, if McDonald's mentions its partnership with NBA star LeBron James, and tags him in the post (as they did below), that post may now appear in news feed for fans of either McDonalds or LeBron. It's a simple way for brands to expand reach, and may mean more brand content in your feed. McDonald's tagged LeBron in this post, meaning it could appear in the news feed of fans of either McDonald's or LeBron.

What You're Seeing Less Of:

'Meme photos' When Facebook decided to highlight more "high quality" content within news feed, there was a necessary corollary: less low quality stuff. What counts as low quality? Facebook has been frustratingly imprecise in its definition, except to say that it's not singling out any particular website for demotion. One example of demoted content the social network gave in this AllThingsD interview late last year: "meme photos." "it’s not like you’re never going to see a funny cat photo from Imgur," said News Feed manager Lars Backstrom. "It’s that maybe you’ll see 10 percent less of that, and 10 percent more articles."

'Spammy' Links Have you ever clicked on a link that takes you to a page full of ads? There are a lot of four-letter words you may use to refer to these links, especially if you get duped into clicking on one, but Facebook is choosing to call them "spammy" — and wants to eliminate them from news feed. The company announced an algorithm tweak last week that will identify posts with "spammy links" and keep them from surfacing to other users. Facebook says that when users visit a link and fail to Like or share the original post, it tends to be spammy. Its not a perfect system, of course, but we appreciate the attempt.

Like-baiting If a post asks you to Like, share or comment, it's gaming the Facebook system. That type of engagement is what helps identify the good posts from the bad posts. The company is trying to put a stop to the posts that actively asks users to Like it. An example of Like-baiting. This was part of the algorithm change announced last week, so you may not notice much of a difference yet. You can also do your part to keep Like-baiting stories away from your friends: hide them.

Ultimately, you have more control over what you see in the News Feed than you may think. The best way to ensure you see what you care about is to engage with the posts you like best (Like, comment, or share them) and hide the ones you don't.