Parts of OSI have influenced Internet protocol development, but none more than the abstract model itself, documented in OSI 7498 and its various addenda. In this model, a networking system is divided into layers. Within each layer, one or more entities implement its functionality. Each entity interacts directly only with the layer immediately beneath it, and provides facilities for use by the layer above it. Protocols enable an entity in one host to interact with a corresponding entity at the same layer in a remote host.
The seven layers of the OSI Basic Reference Model are (from bottom to top):
The original Internet protocol specifications defined a four-level model, and protocols designed around it (like TCP) have difficulty fitting neatly into the seven-layer model. Most newer designs use the seven-layer model.
The OSI Basic Reference Model has enjoyed a far greater acceptance than the OSI protocols themselves. There are several reasons for this. OSI's committee-based design process bred overgrown, unimaginative protocols that nobody ever accused of efficiency. Heavy European dominance helped protect their investments in X.25 (CONS is basically X.25 for datagram networks). Perhaps most importantly, X.25 data networks never caught people's imagination like the Internet, which, with a strong history of free, downloadable protocol specifications, has been loath to embrace yet another networking scheme where you have to pay to figure how things work.
And why should we? OSI's biggest problem is that doesn't really offer anything new. The strongest case for its implementation comes from its status as an "international standard", but we already have a de facto international standard - the Internet. OSI protocols will be around, but its most significant contribution is the philosophy of networking represented by its layered model.
If the Internet community has to worry about anything, it's the danger of IETF turning into another ISO - a big, overgrown standards organization run by committees, churning out thousands of pages of rubbish, and dominated by big business players more interested in preserving investments than advancing the state of the art.