using (var repo = new Repository("path/to/your/repo"))
{
    var RFC2822Format = "ddd dd MMM HH:mm:ss yyyy K";

    foreach (Commit c in repo.Commits.Take(15))
    {
        Console.WriteLine(string.Format("commit {0}", c.Id));
                   
        if (c.Parents.Count() > 1)
        {
            Console.WriteLine("Merge: {0}", 
                string.Join(" ", c.Parents.Select(p => p.Id.Sha.Substring(0, 7)).ToArray()));
        }

        Console.WriteLine(string.Format("Author: {0} <{1}>", c.Author.Name, c.Author.Email));
        Console.WriteLine("Date:   {0}", c.Author.When.ToString(RFC2822Format, CultureInfo.InvariantCulture));
        Console.WriteLine();
        Console.WriteLine(c.Message);
        Console.WriteLine();
    }
}

using (var repo = new Repository("path/to/your/repo"))
{
    var filter = new CommitFilter { SortBy = CommitSortStrategies.Topological | CommitSortStrategies.Reverse };

    foreach (Commit c in repo.Commits.QueryBy(filter))
    {
        Console.WriteLine(c.Id);   // Of course the output can be prettified ;-)
    }
}

using (var repo = new Repository("path/to/your/repo"))
{
    var filter = new CommitFilter {
        ExcludeReachableFrom = repo.Branches["master"],       // formerly "Since"
        IncludeReachableFrom = repo.Branches["development"],  // formerly "Until"
    };

    foreach (Commit c in repo.Commits.QueryBy(filter))
    {
        Console.WriteLine(c.Id);   // Of course the output can be prettified ;-)
    }
}

using (var repo = new Repository(@"path/to/your/repo"))
{
    Tag tagTo = repo.Tags["tag2"];
    Tag tagFrom = repo.Tags["tag1"];

    var filter = new CommitFilter()
    {
        IncludeReachableFrom = tagTo.Target.Sha,
        ExcludeReachableFrom = tagFrom.Target.Sha
    };

    var commits = repo.Commits.QueryBy(filter).ToList();
}

using (var repo = new Repository(@"path/to/your/repo"))
{
    Tag tagTo = repo.Tags["tag2"];
    Tag tagFrom = repo.Tags["tag1"];

    var commitFrom = repo.Lookup<LibGit2Sharp.Commit>(tagFrom.Target.Sha);
    var commitTo = repo.Lookup<LibGit2Sharp.Commit>(tagTo.Target.Sha);

    TreeChanges treeChanges = repo.Diff.Compare<TreeChanges>(commitFrom.Tree, commitTo.Tree);
}