The county court in Colorado is court of limited civil and criminal jurisdiction found in every county in the state. County court magistrates and county court judges in high population counties must be lawyers, but in some rural countries, county court judges may be non-lawyers, and in four rural county courts, there are sitting part-time non-lawyer judges as part of the county court bench. Even the non-lawyer judges, however, tend to be college educated and knowledgable generally, because of the merit selection system for judges that is used in Colorado.
The county court's criminal jurisdiction extends to petty offenses, misdemeanors, pre-arrest process like issuing search and arrest warrants, and certain post-arrest preliminary matters in felony cases. In Denver, in addition to these roles, it also serves as the municipal court for the City and County of Denver with jurisdiction over ordinance violations. I can't speak to that part of its procedures because I don't practice criminal law.
In civil matters, county court has jurisdiction over claims for money up to a jurisdictional limit of $15,000 (plus post-commencement attorneys' fees), eviction actions where the title to the property in question is not in dispute, suits to penalize home owners for home owner's association covenant violations, temporary restraining orders, name change petitions, actions to recover tangible personal property worth not more than $15,000, a few other administrative type matters (registration of foreign U.S. judgments, for example), and claims brought with small claims procedure (which are limited to money claims up to $7,500).
Civil claims in county court are governed primarily by Colorado Rules of Civil Procedure 301-411, which also includes a single rule governing appeals from county court civil cases to district courts.
The county court rules are adapted from parallel Colorado rules of civil procedure applicable in the general jurisdiction district court (which are in turn adapted from the Federal Rules of Civil Procedure), but the adaptation loses a lot in translation. They are clearly drafted by people with little or no experience practicing in county court and are frequently ambiguous in the county court context. The county court also has no counterpart of Colorado Rule of Civil Procedure 121 which fills in the Colorado specific procedural details on essential matters which have no parallel federal rule of civil procedure.
Basically, despite the fact the county court has a much larger case load than district court, and needs rules clear enough for pro se parties who are common in county court to understand, county court is actually the poor stepchild of district court civil procedure and suffers accordingly.