Customs and immigration covers a range of border control procedures (referred to as 'immigration' in most countries) and import of goods. Prefer a more specific tag where appropriate, some examples of which are listed under `tag info`.
Customs is generally the term used when dealing with the import and export of goods; issues such as taxes, prohibited items, duty-free etc.
Immigration is the process by which people are authorized to cross international borders. This includes checks such as travel documents (passports, travel passes) and the ability to entry a country or territory (visas, and visa exceptions).
This tag should be used when your question involves general issues with customs and immigration. Customs and immigration covers border control issues and types of goods allowed to be brought into a country and taxation rules related to them, if any.
More specific tags currently in use include:
borders carnet-de-passage day-counting denial-of-entry deportation global-entry i-94 land-borders nexus passport-stamps pre-clearance trusted-traveler tsa tsa-precheck