diff --git a/src/libse/Common/HtmlUtil.cs b/src/libse/Common/HtmlUtil.cs
index 180a1f341..2c4d63438 100644
--- a/src/libse/Common/HtmlUtil.cs
+++ b/src/libse/Common/HtmlUtil.cs
@@ -367,6 +367,12 @@ namespace Nikse.SubtitleEdit.Core.Common
             return encoded.ToString();
         }
 
+        /// <summary>
+        /// Remove all HTML tags from the input string, optionally including SSA tags.
+        /// </summary>
+        /// <param name="input">The input string that may contain HTML tags.</param>
+        /// <param name="alsoSsaTags">A boolean value indicating whether SSA tags should also be removed.</param>
+        /// <returns>A new string with all HTML tags removed, and optionally SSA tags removed.</returns>
         public static string RemoveHtmlTags(string input, bool alsoSsaTags = false)
         {
             if (input == null || input.Length < 3)
@@ -523,6 +529,11 @@ namespace Nikse.SubtitleEdit.Core.Common
             return new string(array, 0, arrayIndex);
         }
 
+        /// <summary>
+        /// Determines whether the specified text is a URL.
+        /// </summary>
+        /// <param name="text">The text to evaluate.</param>
+        /// <returns>True if the text is considered a URL, otherwise false.</returns>
         public static bool IsUrl(string text)
         {
             if (string.IsNullOrWhiteSpace(text) || text.Length < 6 || text.IndexOf('.') < 0 || text.IndexOf(' ') >= 0)
@@ -546,6 +557,11 @@ namespace Nikse.SubtitleEdit.Core.Common
             return false;
         }
 
+        /// <summary>
+        /// Determines if the provided text starts with a URL-like string.
+        /// </summary>
+        /// <param name="text">The text to examine.</param>
+        /// <returns>True if the text starts with a URL-like string; otherwise, false.</returns>
         public static bool StartsWithUrl(string text)
         {
             if (string.IsNullOrWhiteSpace(text))
@@ -564,6 +580,11 @@ namespace Nikse.SubtitleEdit.Core.Common
 
         private static readonly string[] UppercaseTags = { "<I>", "<U>", "<B>", "<FONT", "</I>", "</U>", "</B>", "</FONT>" };
 
+        /// <summary>
+        /// Converts all uppercase HTML tags in the input string to lowercase.
+        /// </summary>
+        /// <param name="input">The input string containing HTML tags to be converted.</param>
+        /// <returns>A new string with all uppercase HTML tags converted to lowercase.</returns>
         public static string FixUpperTags(string input)
         {
             if (string.IsNullOrEmpty(input) || input.IndexOf('<') < 0)
@@ -588,6 +609,11 @@ namespace Nikse.SubtitleEdit.Core.Common
             return text;
         }
 
+        /// <summary>
+        /// Determines if the provided text contains formattable content not enclosed within HTML-like tags.
+        /// </summary>
+        /// <param name="text">The input text to be checked.</param>
+        /// <returns>True if the text contains any formattable content (letters or digits) outside of HTML-like tags; otherwise, false.</returns>
         public static bool IsTextFormattable(in string text)
         {
             if (string.IsNullOrEmpty(text))
@@ -641,7 +667,12 @@ namespace Nikse.SubtitleEdit.Core.Common
             "< / i >", "< /i>", "</ i>", "< /i >", "</i >", "</ i >",
             "< / i>", "</I>", "< / I >", "< /I>", "</ I>", "< /I >", "</I >", "</ I >", "< / I>", "</i<", "</I<", "</I>"
         };
-        
+
+        /// <summary>
+        /// Fix invalid or improperly formatted italic tags in the input HTML string.
+        /// </summary>
+        /// <param name="input">The input HTML string to process.</param>
+        /// <returns>A string with corrected italic tags.</returns>
         public static string FixInvalidItalicTags(string input)
         {
             var text = input;
@@ -1000,6 +1031,14 @@ namespace Nikse.SubtitleEdit.Core.Common
             return preTags + text;
         }
 
+        /// <summary>
+        /// Toggles the specified HTML or SSA/ASS tag on or off in the provided text.
+        /// </summary>
+        /// <param name="input">The input string to apply the tag toggle.</param>
+        /// <param name="tag">The HTML or SSA/ASS tag to be toggled.</param>
+        /// <param name="wholeLine">Specifies whether the whole line should be toggled or just part of it.</param>
+        /// <param name="assa">Indicates whether the text contains SSA/ASS tags.</param>
+        /// <returns>A new string with the specified tag toggled.</returns>
         public static string ToggleTag(string input, string tag, bool wholeLine, bool assa)
         {
             var text = input;
@@ -1060,6 +1099,14 @@ namespace Nikse.SubtitleEdit.Core.Common
             return text;
         }
 
+        /// <summary>
+        /// Determines if the specified tag is present in the input HTML or SSA/ASS string.
+        /// </summary>
+        /// <param name="input">The input string to search for the specified tag.</param>
+        /// <param name="tag">The HTML or SSA/ASS tag to check for.</param>
+        /// <param name="wholeLine">Specifies whether the search should consider the whole line.</param>
+        /// <param name="assa">Indicates if the input string is in SSA/ASS format.</param>
+        /// <returns>True if the tag is present in the input; otherwise, false.</returns>
         public static bool IsTagOn(string input, string tag, bool wholeLine, bool assa)
         {
             var text = input;
@@ -1079,6 +1126,14 @@ namespace Nikse.SubtitleEdit.Core.Common
                    text.IndexOf("</" + tag + ">", StringComparison.OrdinalIgnoreCase) >= 0;
         }
 
+        /// <summary>
+        /// Applies the specified HTML or ASSA tag to the input string.
+        /// </summary>
+        /// <param name="input">The input string to which the tag will be applied.</param>
+        /// <param name="tag">The tag to apply to the input string.</param>
+        /// <param name="wholeLine">If true, the tag is applied to the entire line; otherwise, the tag is applied to a portion of the line.</param>
+        /// <param name="assa">If true, the tag is treated as an ASSA tag; otherwise, it is treated as an HTML tag.</param>
+        /// <returns>A new string with the specified tag applied.</returns>
         public static string TagOn(string input, string tag, bool wholeLine, bool assa)
         {
             var text = input;
@@ -1125,6 +1180,14 @@ namespace Nikse.SubtitleEdit.Core.Common
             return text;
         }
 
+        /// <summary>
+        /// Remove the specified HTML tag from the input string.
+        /// </summary>
+        /// <param name="input">The input string containing HTML tags.</param>
+        /// <param name="tag">The HTML tag to be removed.</param>
+        /// <param name="wholeLine">Indicates whether the operation applies to the whole line.</param>
+        /// <param name="assa">Indicates whether ASSA (Advanced SubStation Alpha) tags are used.</param>
+        /// <returns>A new string with the specified tag removed.</returns>
         public static string TagOff(string input, string tag, bool wholeLine, bool assa)
         {
             var text = input;
@@ -1174,6 +1237,12 @@ namespace Nikse.SubtitleEdit.Core.Common
             return text;
         }
 
+        /// <summary>
+        /// Converts a string representation of a color to a Color object. The string can be in various formats such as
+        /// "rgb(r, g, b)", "rgba(r, g, b, a)", or a hex color string like "#RRGGBB" or "#RRGGBBAA".
+        /// </summary>
+        /// <param name="s">The string representation of the color.</param>
+        /// <returns>A Color object corresponding to the input string. If the string cannot be parsed, the default color is white.</returns
         public static Color GetColorFromString(string s)
         {
             try
@@ -1229,6 +1298,11 @@ namespace Nikse.SubtitleEdit.Core.Common
             }
         }
 
+        /// <summary>
+        /// Remove color tags from the input string, adjusting for potentially surrounding font tags.
+        /// </summary>
+        /// <param name="input">The string from which to remove color tags.</param>
+        /// <returns>A new string with color tags removed.</returns>
         public static string RemoveColorTags(string input)
         {
             var r = new Regex("[ ]*(COLOR|color|Color)=[\"']*[#\\dA-Za-z]*[\"']*[ ]*");
@@ -1325,6 +1399,11 @@ namespace Nikse.SubtitleEdit.Core.Common
             return s;
         }
 
+        /// <summary>
+        /// Removes ASS and SSA alignment tags from the given string.
+        /// </summary>
+        /// <param name="s">The input string from which to remove the alignment tags.</param>
+        /// <returns>A new string without ASS and SSA alignment tags.</returns>
         public static string RemoveAssAlignmentTags(string s)
         {
             return s.Replace("{\\an1}", string.Empty) // ASS tags alone
@@ -1378,6 +1457,11 @@ namespace Nikse.SubtitleEdit.Core.Common
                 .Replace("{\\a9}", string.Empty);
         }
 
+        /// <summary>
+        /// Remove color tags specific to Advanced SubStation Alpha (ASSA) format from the input string.
+        /// </summary>
+        /// <param name="input">The input string potentially containing ASSA color tags.</param>
+        /// <returns>A new string with all ASSA color tags removed.</returns>
         public static string RemoveAssaColor(string input)
         {
             var text = input;
@@ -1388,7 +1472,12 @@ namespace Nikse.SubtitleEdit.Core.Common
             text = Regex.Replace(text, "\\\\1c&[abcdefghABCDEFGH\\d]*&", string.Empty);
             return text;
         }
-        
+
+        /// <summary>
+        /// Gets the closing HTML tag for the specified opening tag.
+        /// </summary>
+        /// <param name="tag">The opening HTML tag to find the closing pair for.</param>
+        /// <returns>The closing HTML tag corresponding to the specified opening tag.</returns>
         public static string GetClosingPair(string tag)
         {
             switch (tag)
@@ -1399,11 +1488,26 @@ namespace Nikse.SubtitleEdit.Core.Common
             }
             return tag.StartsWith("<font ", StringComparison.Ordinal) ? "</font>" : string.Empty;
         }
-        
+
+        /// <summary>
+        /// Get the corresponding closing character for a given opening character.
+        /// </summary>
+        /// <param name="ch">The opening character to find the closing pair for.</param>
+        /// <returns>The corresponding closing character.</returns>
         public static char GetClosingPair(char ch) => ch == '<' ? '>' : '}';
 
+        /// <summary>
+        /// Determines if the provided HTML tag is an opening tag.
+        /// </summary>
+        /// <param name="tag">The HTML tag to check.</param>
+        /// <returns>True if the tag is an opening tag, otherwise false.</returns
         public static bool IsOpenTag(string tag) => tag.Length > 1 && tag[1] != '/';
 
+        /// <summary>
+        /// Determines whether the specified character is a start tag symbol for HTML or similar markup.
+        /// </summary>
+        /// <param name="ch">The character to check.</param>
+        /// <returns>True if the character is a start tag symbol; otherwise, false.</returns>
         public static bool IsStartTagSymbol(char ch) => ch == '<' || ch == '{';
     }
 }