YaCy is an open source and distributed search engine. It’s written in Java, so it runs on any platform, and it performs web crawls, indexing, and searching. It’s a peer-to-peer (P2P) network, so every user running YaCy joins in the effort to track the internet as it changes from day to day. Of course, no single user possesses a full index of the entire internet because that would take a data center to house, but the index is distributed and redundant across all YaCy users. It’s a lot like BitTorrent (as it uses distributed hash tables, or DHT, to reference index entries), except the data you’re sharing is a matrix of words and URL associations. By mixing the results returned by the hash tables, no one can tell who has searched for what words, so all searches are functionally anonymous. It’s an effective system for unbiased, ad-free, untracked, and anonymous searches, and you can join in just by using it.
But note it defaults to "junior" mode which means that the sites your client crawls are available only to you because no other YaCy client can reach your index entries. For "senior" mode you need to open port 8090 of your router.
See Customize your internet with an open source search engine
A long time ago, the internet was small enough to be indexed by a few people who gathered the names and locations of all websites and listed them each by topic on a page or in a printed book. As the World Wide Web network grew, the "web rings" convention developed, in which sites with a similar theme or topic or sensibility banded together to form a circular path to each member. A visitor to any site in the ring could click a button to proceed to the next or previous site in the ring to discover new sites relevant to their interest.