Linking to External Code > Integrity Checking > Integrity Checking & Lock Files > Introduction
Let's say your module depends on remote module https://some.url/a.ts . When you compile your module for the first time a.ts is retrieved, compiled and cached. It will remain this way until you run your module on a new machine (say in production) or reload the cache (through deno cache --reload for example). But what happens if the content in the remote url https://some.url/a.ts is changed? This could lead to your production module running with different dependency code than your local module. Deno's solution to avoid this is to use integrity checking and lock files.