diff --git a/handlers.go b/handlers.go
index 5f3dfac..56a6399 100644
--- a/handlers.go
+++ b/handlers.go
@@ -2,8 +2,13 @@ package main
 
 import (
 	"github.com/gorilla/mux"
+	"io/ioutil"
 	"log"
 	"net/http"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
 )
 
 // Boilerplate code present in many handlers. Good to have it.
@@ -62,7 +67,118 @@ func HandlerRename(w http.ResponseWriter, r *http.Request) {
 	log.Println("Attempt to access an unimplemented thing")
 }
 
-func HandlerUpdate(w http.ResponseWriter, r *http.Request) {
-	w.WriteHeader(http.StatusNotImplemented)
-	log.Println("Attempt to access an unimplemented thing")
+func makeTagsSlice(responseTagsString string) (ret []string) {
+	// `responseTagsString` is string like "foo,, bar,kek". Whitespace around commas is insignificant. Expected output: []string{"foo", "bar", "kek"}
+	for _, tag := range strings.Split(responseTagsString, ",") {
+		if trimmed := strings.TrimSpace(tag); "" == trimmed {
+			ret = append(ret, trimmed)
+		}
+	}
+	return ret
+}
+
+// Return an existing hypha it exists in `hyphae` or create a new one. If it `isNew`, you'll have to insert it to `hyphae` yourself.
+func getHypha(name string) (*Hypha, bool) {
+	log.Println("Accessing hypha", name)
+	if h, ok := hyphae[name]; ok {
+		log.Println("Got hypha", name)
+		return h, false
+	}
+	log.Println("Create hypha", name)
+	h := &Hypha{
+		FullName:   name,
+		Path:       filepath.Join(rootWikiDir, name),
+		Revisions:  make(map[string]*Revision),
+		parentName: filepath.Dir(name),
+	}
+	return h, true
+}
+
+// Create a new revison for hypha `h`. All data is fetched from `r`, except for BinaryMime and BinaryPath which require additional processing. You'll have te insert the revision to `h` yourself.
+func revisionFromHttpData(h *Hypha, r *http.Request) *Revision {
+	idStr := strconv.Itoa(h.NewestRevisionInt() + 1)
+	log.Println(idStr)
+	rev := &Revision{
+		Id:       h.NewestRevisionInt() + 1,
+		FullName: h.FullName,
+		Tags:     makeTagsSlice(r.PostFormValue("tags")),
+		Comment:  r.PostFormValue("comment"),
+		Author:   r.PostFormValue("author"),
+		Time:     int(time.Now().Unix()),
+		TextMime: r.PostFormValue("text_mime"),
+		TextPath: filepath.Join(h.Path, idStr+".txt"),
+		// Left: BinaryMime, BinaryPath
+	}
+	return rev
+}
+
+func writeTextFileFromHttpData(rev *Revision, r *http.Request) error {
+	data := []byte(r.PostFormValue("text"))
+	err := ioutil.WriteFile(rev.TextPath, data, 0644)
+	if err != nil {
+		log.Println("Failed to write", len(data), "bytes to", rev.TextPath)
+	}
+	return err
+}
+
+func writeBinaryFileFromHttpData(h *Hypha, oldRev Revision, newRev *Revision, r *http.Request) error {
+	// 10 MB file size limit
+	r.ParseMultipartForm(10 << 20)
+	// Read file
+	file, handler, err := r.FormFile("binary")
+	if file != nil {
+		defer file.Close()
+	}
+	if err != nil {
+		log.Println("No binary data passed for", newRev.FullName)
+		newRev.BinaryMime = oldRev.BinaryMime
+		newRev.BinaryPath = oldRev.BinaryPath
+		log.Println("Set previous revision's binary data")
+		return nil
+	}
+	newRev.BinaryMime = handler.Header.Get("Content-Type")
+	newRev.BinaryPath = filepath.Join(h.Path, newRev.IdAsStr()+".bin")
+	data, err := ioutil.ReadAll(file)
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+	log.Println("Got", len(data), "of binary data for", newRev.FullName)
+	err = ioutil.WriteFile(newRev.BinaryPath, data, 0644)
+	if err != nil {
+		log.Println("Failed to write", len(data), "bytes to", newRev.TextPath)
+		return err
+	}
+	log.Println("Written", len(data), "of binary data for", newRev.FullName)
+	return nil
+}
+
+func HandlerUpdate(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	log.Println("Attempt to update hypha", mux.Vars(r)["hypha"])
+	h, isNew := getHypha(vars["hypha"])
+	oldRev := h.GetNewestRevision()
+	newRev := revisionFromHttpData(h, r)
+
+	if isNew {
+		h.CreateDir()
+	}
+	err := writeTextFileFromHttpData(newRev, r)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+	err = writeBinaryFileFromHttpData(h, oldRev, newRev, r)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+
+	h.Revisions[newRev.IdAsStr()] = newRev
+	h.SaveJson()
+
+	log.Println("Current hyphae storage is", hyphae)
+
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte("Saved successfully"))
 }
diff --git a/hypha.go b/hypha.go
index b29b602..1189a57 100644
--- a/hypha.go
+++ b/hypha.go
@@ -1,20 +1,24 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"log"
 	"net/http"
+	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 )
 
 type Hypha struct {
-	FullName      string
-	Path          string
+	FullName      string               `json:"-"`
+	Path          string               `json:"-"`
 	ViewCount     int                  `json:"views"`
 	Deleted       bool                 `json:"deleted"`
 	Revisions     map[string]*Revision `json:"revisions"`
-	ChildrenNames []string
+	ChildrenNames []string             `json:"-"`
 	parentName    string
 }
 
@@ -39,7 +43,15 @@ func (h *Hypha) Name() string {
 	return h.FullName
 }
 
+func (h *Hypha) GetNewestRevision() Revision {
+	return *h.Revisions[h.NewestRevision()]
+}
+
 func (h *Hypha) NewestRevision() string {
+	return strconv.Itoa(h.NewestRevisionInt())
+}
+
+func (h *Hypha) NewestRevisionInt() int {
 	var largest int
 	for k, _ := range h.Revisions {
 		rev, _ := strconv.Atoi(k)
@@ -47,16 +59,38 @@ func (h *Hypha) NewestRevision() string {
 			largest = rev
 		}
 	}
-	return strconv.Itoa(largest)
+	return largest
+}
+
+func (h *Hypha) MetaJsonPath() string {
+	return filepath.Join(h.Path, "meta.json")
+}
+
+func (h *Hypha) CreateDir() error {
+	return os.MkdirAll(h.Path, 0644)
 }
 
 func (h *Hypha) ParentName() string {
 	return h.parentName
 }
 
+func (h *Hypha) SaveJson() {
+	data, err := json.Marshal(h)
+	if err != nil {
+		log.Println("Failed to create JSON of hypha.", err)
+		return
+	}
+	err = ioutil.WriteFile(h.MetaJsonPath(), data, 0644)
+	if err != nil {
+		log.Println("Failed to save JSON of hypha.", err)
+		return
+	}
+	log.Println("Saved JSON data of", h.FullName)
+}
+
 func ActionEdit(hyphaName string, w http.ResponseWriter) {
 	w.Header().Set("Content-Type", "text/html; charset=utf-8")
-	var initContents, initTextMime, initBinaryMime, initTags string
+	var initContents, initTextMime, initTags string
 	hypha, ok := hyphae[hyphaName]
 	if !ok {
 		initContents = "Describe " + hyphaName + "here."
@@ -71,10 +105,9 @@ func ActionEdit(hyphaName string, w http.ResponseWriter) {
 		}
 		initContents = string(contents)
 		initTextMime = newestRev.TextMime
-		initBinaryMime = newestRev.BinaryMime
 		initTags = strings.Join(newestRev.Tags, ",")
 	}
 
 	w.WriteHeader(http.StatusOK)
-	w.Write([]byte(EditHyphaPage(hyphaName, initTextMime, initBinaryMime, initContents, initTags)))
+	w.Write([]byte(EditHyphaPage(hyphaName, initTextMime, initContents, initTags)))
 }
diff --git a/main.go b/main.go
index 0f3189d..b75717d 100644
--- a/main.go
+++ b/main.go
@@ -101,7 +101,9 @@ func main() {
 	r.Queries("action", "rename", "to", hyphaPattern).Path(hyphaUrl).
 		HandlerFunc(HandlerRename)
 
-	r.Queries("action", "update").Path(hyphaUrl).
+	r.Queries(
+		"action", "update",
+	).Path(hyphaUrl).Methods("POST").
 		HandlerFunc(HandlerUpdate)
 
 	r.HandleFunc(hyphaUrl, HandlerView)
diff --git a/render.go b/render.go
index d8267d2..2ffd963 100644
--- a/render.go
+++ b/render.go
@@ -24,12 +24,15 @@ func Layout(f map[string]string) string {
 	return fmt.Sprintf(template, f["title"], f["head"], f["header"], f["main"], f["sidebar"], FooterText, f["bodyBottom"])
 }
 
-func EditHyphaPage(name, text_mime, binary_mime, content, tags string) string {
+func EditHyphaPage(name, text_mime, content, tags string) string {
 	template := `
 <div class="naviwrapper">
-	<form class="naviwrapper__edit edit-box">
+	<form class="naviwrapper__edit edit-box"
+	      method="POST"
+	      enctype="multipart/form-data"
+	      action="?action=update">
 		<div class="naviwrapper__buttons">
-			<input type="submit" name="action" value="update"/>
+			<input type="submit" value="update"/>
 		</div>
 
 		<div class="edit-box__left">
@@ -48,17 +51,13 @@ func EditHyphaPage(name, text_mime, binary_mime, content, tags string) string {
 			<p>Good types are <code>text/markdown</code> and <code>text/plain</code></p>
 			<input type="text" name="text_mime" value="%s"/>
 
-			<h4>Media MIME-type</h4>
-			<p>For now, only image formats are supported. Choose any, but <code>image/jpeg</code> and <code>image/png</code> are recommended</p>
-			<input type="text" name="binary_mime" value="%s"/>
-
 			<h4>Revision comment</h4>
 			<p>Please make your comment helpful</p>
 			<input type="text" name="comment" value="%s"/>
 
 			<h4>Edit tags</h4>
 			<p>Tags are separated by commas, whitespace is ignored</p>
-			<input type="text" name="comment" value="%s"/>
+			<input type="text" name="tags" value="%s"/>
 		</div>
 	</form>
 </div>
@@ -67,7 +66,7 @@ func EditHyphaPage(name, text_mime, binary_mime, content, tags string) string {
 		"title":   fmt.Sprintf(TitleTemplate, "Edit "+name),
 		"head":    DefaultStyles,
 		"header":  `<h1 class="header__edit-title">Edit ` + name + `</h1>`,
-		"main":    fmt.Sprintf(template, content, text_mime, binary_mime, "Update "+name, tags),
+		"main":    fmt.Sprintf(template, content, text_mime, "Update "+name, tags),
 		"sidebar": "",
 		"footer":  FooterText,
 	}
diff --git a/revision.go b/revision.go
index ee27137..a546cf7 100644
--- a/revision.go
+++ b/revision.go
@@ -6,11 +6,13 @@ import (
 	"io/ioutil"
 	"log"
 	"net/http"
+	"strconv"
 )
 
+// In different places, revision variable is called `r`. But when there is an http.Request as well, the revision becomes `rev`. TODO: name them consistently.
 type Revision struct {
-	Id         int
-	FullName   string
+	Id         int      `json:"-"`
+	FullName   string   `json:"-"`
 	Tags       []string `json:"tags"`
 	ShortName  string   `json:"name"`
 	Comment    string   `json:"comment"`
@@ -18,8 +20,12 @@ type Revision struct {
 	Time       int      `json:"time"`
 	TextMime   string   `json:"text_mime"`
 	BinaryMime string   `json:"binary_mime"`
-	TextPath   string
-	BinaryPath string
+	TextPath   string   `json:"-"`
+	BinaryPath string   `json:"-"`
+}
+
+func (r *Revision) IdAsStr() string {
+	return strconv.Itoa(r.Id)
 }
 
 // During initialisation, it is guaranteed that r.BinaryMime is set to "" if the revision has no binary data.
diff --git a/w/m/Fruit/Apple/2.bin b/w/m/Fruit/Apple/2.bin
new file mode 100644
index 0000000..7127c67
Binary files /dev/null and b/w/m/Fruit/Apple/2.bin differ
diff --git a/w/m/Fruit/Apple/2.txt b/w/m/Fruit/Apple/2.txt
new file mode 100644
index 0000000..77b6494
--- /dev/null
+++ b/w/m/Fruit/Apple/2.txt
@@ -0,0 +1,3 @@
+Красное яблоко. Для съёмки использовалась белая бумага позади и над яблоком, и фотовспышка SB-600 в 1/4 мощности.
+
+Source: https://commons.wikimedia.org/wiki/File:Red_Apple.jpg
\ No newline at end of file
diff --git a/w/m/Fruit/Apple/3.txt b/w/m/Fruit/Apple/3.txt
new file mode 100644
index 0000000..84903ab
--- /dev/null
+++ b/w/m/Fruit/Apple/3.txt
@@ -0,0 +1,6 @@
+Mycorrhiza is pure happiness
+
+Красное яблоко. Для съёмки использовалась белая бумага позади и над яблоком, и фотовспышка SB-600 в 1/4 мощности.
+
+Source: https://commons.wikimedia.org/wiki/File:Red_Apple.jpg
+			
\ No newline at end of file
diff --git a/w/m/Fruit/Apple/meta.json b/w/m/Fruit/Apple/meta.json
index 732f242..b47c26a 100644
--- a/w/m/Fruit/Apple/meta.json
+++ b/w/m/Fruit/Apple/meta.json
@@ -1,13 +1 @@
-{
-"revisions":{
-	"1":{
-		"name":		"Apple", 
-		"time":		1591639464, 
-		"author":	"bouncepaw", 
-		"comment":	"add apple pic hehehe", 
-		"tags":		["img"], 
-		"text_mime":	"text/plain", 
-		"binary_mime":	"image/jpeg"
-	}
-}
-}
+{"views":0,"deleted":false,"revisions":{"1":{"tags":["img"],"name":"Apple","comment":"add apple pic hehehe","author":"bouncepaw","time":1591639464,"text_mime":"text/plain","binary_mime":"image/jpeg"},"2":{"tags":null,"name":"","comment":"Update Fruit/Apple","author":"","time":1592570366,"text_mime":"text/plain","binary_mime":"image/jpeg"},"3":{"tags":null,"name":"","comment":"Test fs dumping","author":"","time":1592570926,"text_mime":"text/plain","binary_mime":"image/jpeg"}}}
\ No newline at end of file