This filter looks only at the end of each line. A line is removed when it finishes with the string you specify, and kept otherwise — regardless of what appears earlier in it.
Why the anchor matters
Anchoring to the end avoids the false positives that plague open substring matching. Removing lines ending in .pdf takes the PDFs and leaves /guides/pdf-tips alone, which an unanchored filter would not.
Where it fits naturally
File extensions sit at the end of URLs. So do trailing slashes, query-string tails, and file-type markers in export filenames. Any of those is a clean end-anchored filter.
The counterpart
Filtering by how a line starts is the same operation at the other end, and the two are often used in sequence to narrow a list from both directions.
Try it: Remove Lines Ending With on SeoWolf's Notepad.