Problem:
Metadata downloaded from the internet, though having the same file name and residing in the same folder as the actual data, is not visible in ArcCatalog when the Metadata tab is clicked.

Solution:
Covert the metadata into FGDC- compliant format (if not already so) and "Save As" text. Then use the "import metadata" function in ArcCatalog to bring it in. This process creates an xml file that can be read by ArcCatalog.

Background:
Metadata, literally data about data, are commonly available as a separate file when downloading spatial data from the internet. This information is as important as the data themselves, and should travel with the data as it is used, moved from folder to folder, shared, etc. Moreover, a standard (actually several) now exists for recording metadata so all might share common attributes. The most widely used standard in this country is the FGDC (Federal Geographic Data Committee) standard, which was adopted by the US gov. in 1994 (see http://www.fgdc.gov for further details). By executive order, all USGS and other federally distributed geospatial data are suppose to be accompanied by FGDC metadata, and many other organizations (e.g. states, counties, cities, etc.) have adopted this standard as well.

The FGDC standard has been adapted to several different styles; you may have seen a Frequently Asked Questions (FAQ) style, a "classic" style, a couple of different ESRI style, and others. These are nothing more than different layout of the same data, coded to display in different ways. ArcCatalog permits viewing FGDC data in any of these styles ("stylesheets"), generating any of these styles on-the-fly.

However, in order to see these data in ArcCatalog, they must first be in a format that it can recognize (i.e. xml); see the Help file on Metadata for more info. To fix this problem follow the steps below.
 

Steps:
N.B. These procedures will only work for FGDC- compliant metadata. If not FGDC compliant, the only alternative I know of at this time is to manually cut and paste metadata into ArcCatalog using the metadata editing function. An FGDC metadata compiler for data already parsed to an appropriate text format can be found at http://geology.usgs.gov/tools/metadata/tools/doc/mp.html.

1) After downloading FGDC metadata, determine their format. In some (most?) cases this will be indicated by the file extension (e.g. htm, html, txt). For all but data formatted in Xml or Sgml, the data will have to cleaned of extraneous characters and lines, saved as text with a .txt file extension, then imported using the ArcCatalog metadata importing function. I have encountered the following common situations with these easy work-arounds:

a) FGDC metadata available as htm or html files. These will have a series of hyperlinks at the top of the page that need to be removed before saving as text.
- save the metadata webpage as text, using the "Save As" command under the File menu in Internet Explorer
- Open the file in a text editor (e.g. Notepad or Wordpad) and delete the hyperlink lines
at the beginning of the document. After cleaning, the document should start with:

Identification_Information:
Citation:
Citation_Information:
Originator:

- Scroll to the end of the document and remove any special characters that might be there.

- Save the file with the same name as the dataset, but with a .txt extension, in the folder containing the data.

b) FGDC metadata with .met or .txt extensions. These files will already be in text format but will sometimes contain spurious characters at the beginning or end of the document.
- As above, open the file in a text editor and delete any spurious characters at the beginning and end of the document, then save as text with the same name as the dataset and in the same location.

c) FGDC metadata saved in SGML format. Yahoo! This can be imported as is!

d) FGDC metadata saved with a .fgd extension. These will have section numbers before each metadata section that will need to be (tediously) removed before saving with a text extension. I know of no easy way to do this and haven't attempted it yet.

2) Within ArcCatalog, browse to the dataset, click the metadata tab in the right window, and click the import metadata tool.

3) In the import metadata dialog box, set the Format to txt, browse to your metadata file location, and click OK.
-this step creates a new file in xml format, which is automatically save in the same folder and given the same name, but with an .xml extension, as the data file.

4) Click the metadata tab in the window on the right, then the content tab. You should now see the metadata.